When Richard George Rowallen, 14th Earl of Hartwood, one-time army colonel, ex-MI5, a senior official of the National Crime Agency, was murdered the repercussions were enormous. The killing sent shudders through the latter organization, MI5, MI6, his old regiment, the Metropolitan Police and other forces, not to mention his many friends. His professional name, a pseudonym, had been Richard Daws.

'But he lived in a castle with any number of security devices and a bodyguard!' my husband Patrick burst out with, furious, grieving, tears in his eyes.

Privately, I was more upset about the bodyguard, whom we had only ever known as Jordon, a charming and highly educated young man who had also acted as butler. It was a relief to know that Daws' wife Pamela had not been harmed in the attack, which had happened at night. A bad sleeper, she had her own rooms.

And as Patrick had said, how had the killer penetrated the security?

Patrick is an 'adviser' to the NCA and I work as a part-time 'consultant', mostly to him, the quotation marks important as, so far, the job has been very much hands on. The rest of the time I am an author. Prior to Daws' murder, we had been told, by him, that if proposals he had been working on were accepted we would be offered different, less hazardous positions due to what he had described as restructuring. At the time these new roles were unspecified. I knew Patrick would possibly find this new direction in his career tedious – more time spent in an office perhaps and possible stints of giving training lectures – after a very active life also spent in the army and MI5. I was welcoming the change as we were responsible for five children, three of our own and two adopted after Patrick's brother, Larry, was killed. Not only that, we were getting older.

The media had described Daws as a senior adviser to the National Crime Command, which is a branch of the NCA, but he had been far more than that and the position was too important to leave unfilled for any length of time. Not long afterwards a new person was appointed, temporarily or not, no one seemed to know – a woman by the name of Marcia Lindersland. She immediately tossed out the proposed restructuring arrangements and announced that she would shortly publish her own. The seismographs continued to tremble as although it appeared that she was being given free rein there were mutterings that she did not really have that kind of authority. We decided to keep our heads down and Patrick carried on working on routine matters at HQ in London during the week, and came home to Hinton Littlemore, Somerset, for the weekends.

Meanwhile, Sussex Police were investigating the murder while suffering from a dire shortage of evidence. Everything was being made more complicated by the fact that for the first time in its history certain parts of the castle were now open to the public. Worse, the security system in the private apartments had failed to detect the intruders, which apparently baffled the installers who were brought in to check and advise.

As far as any further security was concerned there were two gun dogs and Pamela's dachshund on the premises, but they were kept in what was described as a boot room at the rear overnight and if they had barked no one had heard them. This was understandable as castles are large and Daws and his wife's accommodation, an extensive apartment, was situated on what he had always referred to as the top floor of a wing added in his great-grandfather's time – not quite correct as above that there were equally extensive attics. On the ground floor there were additional private rooms, although the general public was allowed to look into them from the doorways, that were used for large-scale entertaining at Christmas and when Pamela hosted meetings and receptions for the various charities with which she was involved.

Eventually, when the police had released Daws' body a few weeks later, no further in their investigation, the funeral, which we attended, took place, followed by internment in the family vault in the pretty parish church. It was a surprisingly small and muted affair in the village of Hartwood that had, over the centuries, grown up around the castle. This was situated on what had obviously been regarded as a strategic spot on the South Downs. We were told that, in several months' time, there would be memorial service in London.

All this was in the public eye. It had been made known that the NCA was liaising with Sussex Police but nothing had been said about the fact that the security services had been immediately involved, a fact revealed to me by Patrick. This insider knowledge had come from Commander Michael Greenway, Patrick's immediate boss. Greenway then hinted to me in a conversation when I had rung him about a routine matter that there were also other undercurrents that ran dark and deep. He had given no details.

Patrick had been asked if he would act as one of the pall bearers, a great honour and proof that one person at least was aware that he had been Daws' protégé. I had an idea that Pamela, Lady Rowallen, whom we had met on several occasions, might have been behind this as she was fully aware that the apprenticeship had been an extremely tough one. But no mention of this was made when we were invited by her to go to the castle after the funeral, although I noticed that she had given my husband a very warm smile when she first caught sight of him.

A simple service, then, in a country church. Daws had served his country well during a long career. He had been older when he died than I had thought – sixty-nine – and it had been brought to an end in a vicious and calculated manner. But I still wept a few tears for Jordon, who had died with him. His funeral had taken place a week earlier, somewhere in the north of England.

Ashes to ashes, dust to dust.

Later, I rather felt that Marcia Lindersland – why was she present when the rest of the mourners gave every impression of being mostly friends and family? – whom I had not met before, was behaving as though she was some kind of guest of honour. With the benefit of height she was around six feet tall, wore a large hat more suited to Ascot Ladies' Day and towered over just about everyone present. Dressed all in black for the occasion and seemingly prone to utilizing dramatic body language, here was someone who expected to be the centre of attention.

'Just your sort of female,' Patrick whispered to me wryly.

Why is it that one sometimes dislikes a person on sight?

But the moment passed. We stayed for as long as politeness demanded, chatting to people we didn't know, and then made a move to depart.

'You will come and see me, won't you?' Pamela said quietly as we took our leave of her. 'I really mean it; I'm not just making polite noises. I'd like to talk to you about what happened.'

We promised her that we would.

The gathering was being held in the large beamed sitting room in the private apartment and people had spilled out into an area that was almost as big at the head of a wide staircase. Marcia Lindersland, to whom so far we had not spoken, appeared to be holding court there, unwittingly perhaps standing right in front of a shield on the wall bearing the family's arms.

Fixing us with her sharp gaze across the heads of others, she called, 'Monday, my office, ten thirty. All right?'

'No, sorry,' Patrick answered. 'I'm having Monday off.'

Well, he was now.

'That's not convenient,' she snapped back.

'I'll give you a ring when I get in on Tuesday morning,' he replied, squeezed my arm and we left.

'Not your sort of female?' I queried gently when we were in the car.

'Am I getting old and cranky or was she damned rude?'

Oh, yes, terribly, terribly rude.

I fully intended to turn up as well in response to this summons and reckoned I had every right to as Patrick and I do, for most of the time, work together. My intuition, however – what my father used to call my cat's whiskers – was telling me, loud and clear, that there would be trouble.

There was, instantly.

'I don't think we need Mrs Gillard,' Marcia Lindersland said with not so much as a 'good morning' as soon as we walked through her office door on the following Wednesday.

'Ingrid is my working partner,' Patrick answered, looking astounded. 'She's on the payroll. It's official. You must know that.'

'She is not part of the restructuring,' the woman countered.

'In that case I resign.'

She rose to her feet, her pale face flushed with anger. 'Daws always said that you were difficult.'

'Then I'm absolutely delighted to be able to live up to his opinion of me,' Patrick retorted.

There were a few moments' silence during which I pondered the 'always'. Daws had never once mentioned the woman to us. And then she reseated herself and gestured wordlessly to the two chairs facing her desk. Patrick immediately moved them a little farther away, near the wall and out of venom spitting distance, perhaps, and we sat down.

This had been Daws' office, I had to remind myself, and she obviously wasn't superstitious either as it was Room 13. It was a slight shock not to see the cabinets containing his jade collection and the room seemed soulless without the steady tick of his grandfather clock and the various small paintings on the walls that had been in his previous office. There was nothing here that gave even a hint of the personality of the woman in front of us. She looked less imposing without the large black hat she had been wearing when we had last seen her but, nevertheless, here was someone with attitude. Her hair, also black, was cut in a bob with the ends flicked under, just touching the shoulders of the jacket of her very expensive grey suit, which she wore with a white blouse. No jewellery except for tiny gold stud earrings, no wedding ring, her hands tiny – I reluctantly deleted the bitchy 'useless looking' from my mind – like those of a child.

'You're aware of the National Crime Command's Four Pillars of Strategy, I hope,' Lindersland began, making a point of addressing Patrick only.

'Pursue, protect, prevent and prepare,' he obediently recited.

Was it my imagination or was she disappointed that he had remembered or, come to think of it, actually bothered to read it up?

'That's right. And I'm sure you also know that since the NCA was set up it has been decided that each Regional Organised Crime Unit shall have a senior officer from the NCA embedded in it.'

'I am aware of that.'

'It was what Richard Daws had planned for you, within the Avon and Somerset Police Force. Which is the area where you live, I understand.'

Patrick said, 'I do, but Daws hadn't actually gone into details of what he had in mind when we last saw him.'

'No. I'm of the opinion that your "talents" will be wasted in a region that has such low crime rates.'

Yes, she really had said it like that, a finely plucked, or perhaps threaded, eyebrow quirked for good measure.

'A city posting would be preferable for all concerned, don't you think?' she continued.

'Have you ever been to Bath or Bristol?' Patrick asked her.

'No.'

'They're cities.'

There was another silence broken by Patrick saying, 'In view of various assignments in the past that have taken a physical and mental toll on the pair of us and the fact that we have five children —'

'Oh, I know all about that,' she broke in with. 'My predecessor had a mind to give you an easier job. He was entitled to, of course. I think he pandered to the pair of you over the years as he was fond of you. I can't afford to be like that – it's dreadfully unprofessional.'

I found myself coming up to the boil.

'I'll do you a deal,' Patrick said. 'In order to get the local posting that I would prefer – and don't entertain for one second that there's anything easy in crime prevention and catching criminals in that area – I will undertake to arrest whoever killed Richard Daws and/or find out who was behind it.'

'No,' was the immediate reply.

'You're not thinking.'

'The NCA's already involved with that, liaising with Sussex Police.'

'Liaising's no bloody good.' He left it at that, sat back and stared at her.

'No,' she said again.

'You're still not thinking.'

'I have thought, at length. I want you to stay right here, in London, and carry on as you were before but without your wife.'

Patrick gave her a broad smile. 'So who said to you something along the lines of "batter down Patrick Gillard and get him eating out of your hand to prove that you're the man – sorry, woman – for the job"?'

She bridled. 'No one!'

'OK,' he said, getting to his feet. 'Suppose I just go and find Daws' killer anyway?'

'If you do that I will expect your resignation.'

'In that case, ma'am, I shall be happy to hand it to you.'

Outside, in the corridor, I could not contain myself. 'She strung you along! Made you start to think that she was going to give you the West Country job!'

'Coffee,' was all my husband said just then. 'Strong coffee.'

Daws had revealed, on the last occasion we had seen him, that he was proposing to put Michael Greenway's name forward to take over from him when he retired in roughly twelve months' time. He had added that the commander was aware of this. But if Greenway was chewing the landscape about the recommendation coming to nought he gave no sign of it, greeting us cheerfully when we ran him to earth around a quarter of an hour later as he was leaving a meeting. We had not seen him for a while as he had been abroad when Daws' funeral had taken place.

'I can see by your faces that something's wrong,' he said, and set off in a direction that would lead us out of the main entrance of the building. 'Decent coffee, then. Somewhere else. Follow me.'

It was still just as hot and humid as when we had first arrived and as we crossed the road there was a distant rumble of thunder audible above the traffic. However, we did not have far to go, our destination a new restaurant that clearly the commander had patronized before. We were all subdued, and except for Patrick remarking that it would really make his morning to be struck by lightning, nothing else was said until we were seated in a quiet corner and were placing our order. The place was practically empty.

'Kids OK?' Greenway asked laconically.

'Thank you, you've just reminded me that five young people are far more important than my job,' Patrick said quietly. 'Yes, fine.'

'Still got to feed 'em, though,' the commander said with a chuckle.

They went on talking.

Feeling as though I might as well be Patrick's fluffy toy mascot with about as much to say, my contribution to the day having so far been sweet zilch, I miserably stirred my coffee. Patrick related what had happened and Greenway had commiserated, telling him that Lindersland had upset quite a few people since her arrival but not to worry, there was a job to be done so best get on with it.

'I'm not going to knuckle down and carry on working the way I have been,' Patrick said. 'And if she's writing Ingrid out of it I don't want to work for the NCA at all.'

The spoon Greenway was wielding to put three lumps of sugar in his coffee looked like a toy in his large hand. Everything about him is large. He is at least two inches taller than Patrick, who is six foot two, and good looking in a slightly battered way, indicating time once spent playing sports of various kinds. His mane of ash-blond hair, as usual, like Boris Johnson's, needed a refit. Right now his green eyes fixed on me.

'The lady author's despondent,' he observed gently.

I actually felt like crying but swallowed hard and said instead, 'In just a few words she destroyed everything Patrick and I have achieved.'

'Oh, she's a bitch all right,' Greenway responded briskly. 'You'll have to have her come to a sticky end in one of your books.'

This was him all over, at times somewhat without understanding, although I would not wish to describe him as shallow. I gave him a wan smile then went on drinking my coffee.

'I'm going after who killed Daws,' Patrick said into the silence.

'You really meant it!' I exclaimed, shocked out of my gloom.

'I wasn't just winding her up.'

'I thought you might have been fishing for information about the inquiry, that's all.'

'I didn't get any, did I?'

'I understand we're closely liaising with Sussex Police,' Greenway murmured.

'We understand that too but it's hardly unexpected,' Patrick replied sharply. 'And who's "we"?'

The commander shrugged. 'Pass. But you mustn't get the impression that nothing's being done by us.'

'Pass!' Patrick exploded. 'You don't know?'

'Everything's a bit chaotic right now. I'll find out, though.'

'What about the undercurrents you hinted at around a week after the murder occurred?'

'Well, apparently MI5 and MI6 are involved.'

'I already knew that too. And it's understandable as he worked for one and his cases sometimes touched on the other. What about this deeper and darker involvement of someone or something?'

The other man smiled without humour. 'I think those must be words from an inventive imagination.' Again, he looked at me.

'Yes, you dropped a hint,' I agreed. 'When I contacted you about a report I'd recently sent you.'

'Oh, it's nothing dramatic.'

'And you can't tell us?' I persisted.

'I was told the information must go no further.'

'Instructions from Lindersland?'