We were reluctantly shown in again and waited, perched on the sofa, while Allerton and Boulet retreated to the kitchen, ostensibly to make some tea, but we clearly heard their voices conversing in urgent whispers. After a while they came back out. Allerton was carrying a tray with the expected tea things, but his taut, pale face made it clear the words he and Boulet had exchanged were far more important. Boulet was also pale, but his mouth was tightly compressed into a thin, hard line, as though he was determined not to utter a single word.

Allerton poured the tea, and for a couple of minutes we played through the pantomime as though we were welcome guests, unaware of the tense, strained atmosphere.

I took the proffered teacup and stirred it absently while thinking. I suspected I had an idea of the situation and wanted to be thoroughly sure I expressed myself carefully rather than blundering and scaring the two of them off. Poirot would have been amazed at my behaviour I thought, and almost gave a rueful smile at that, but I no longer had him here to smooth ruffled feathers, so I considered my words more carefully than was my usual inclination before speaking.

"Before you say anything I want you to understand that whatever you tell us will be treated with the strictest confidence and not given to the police unless it's absolutely necessary and only with your agreement." I took a sip of the tea. "I also want to tell you that I think I understand what your situation is, and I don't judge it wrong, and certainly not something people should be arrested for." I kept my gaze on them steadily as I spoke. "You're not the only men that have found they preferred other men to women."

I heard Miss Lemon's breath catch ever so slightly at my words, and hoped she wouldn't betray any bias against them, if that was what she thought. Allerton flushed deeply at my words, but I saw the taut expression on his face relax ever so slightly. "You – do you mean that you and mister Poirot-?" He asked.

I almost smiled at that. I suppose it was an obvious question. "No. I loved him, but never like that. I had a couple of men in my command in the war that had the same tendencies. They were a couple of the bravest men I knew, certainly not… degenerates, or whatever we're supposed to think. I kept their secret and never reported them."

Allerton glanced at Boulet in a way that reminded me of couples that seemed to communicate in silence and then said "You're right, Captain Hastings. Michiel and I met five years ago." His hand went to the other man's, and their fingers laced together.

"The ambassador had ordered a custom-made bracelet for his wife's birthday; Stephen was delivering it." Boulet said. "I ran into him there, and – well," he gave a shrug, looking almost sheepish.

"But I imagine someone else found out." I said.

Allerton nodded, a deeply unhappy expression settling on his face. "You're right, Captain Hastings. I received a letter about six weeks ago, a horrible, blackmailing letter." He swallowed. "It said that unless we did what they wanted, the authorities would learn of our relationship."

"Did they have proof?" Miss Lemon asked.

"There was a photograph with the letter. They claimed they had more that were more…intimate." Boulet said. "You know how the law feels about homosexual men in this country, I'm sure. It's not an offence in my own country, but I would still be extradited back to my homeland in disgrace, and Stephen-" his fingers tightened briefly on the other man's. "Stephen would be imprisoned."

"It's not just that, Captain Hastings. My father is a minister in the local church at home, and would condemn me as deserving to burn in eternal hellfire if he knew about us." Allerton said. He shrugged hopelessly. "Anyway, the letter was followed by another that gave instructions that Michiel was to steal some of the plans about the work on aeroplanes that was being carried out by the Belgian embassy and send them to a sub post office in London."

"And you did."

Boulet nodded. "Yes. I was ashamed - I am ashamed of what I did, but I couldn't let Stephen take the consequences if I hadn't." He met my gaze steadily. "I didn't kill Poirot though, Captain Hastings; I swear to you on my own soul that I didn't."

I sat in silence for a minute, thinking. I was sure Boulet was telling the truth – he had stolen the plans, but hadn't had any hand in murdering Poirot. "No, I don't believe you did." I told him. I was sure the blackmailer had done it, although there was something about that surmise that nagged at me, but I couldn't think what it was. I mentally shrugged, telling myself I'd think about it later. "Do you still have the letters?" I asked.

"Yes; I'll get them for you if you want them." Allerton offered. At my nod he disappeared into another room and came back with a couple of letters in his hands. He handed them to me and I glanced at the envelopes. The address was typed, and when I removed one of the letters it proved to be also typed on cheap paper – nothing to indicate who it was sent by.

"Do you mind if I keep these for now?" I asked.

Allerton raised both his hands in an almost dismissive gesture. "Keep them as long as you like, and feel free to destroy them if you will, Captain Hastings. Just please don't permit them to come to anyone else's attention."

"I shan't." I assured him. I glanced over at Miss Lemon. "Is there anything else we need to know?"

She shook her head. "I don't believe so, Captain Hastings."

I got to my feet. "Well, thank you both for your honesty."

"You said you'd take what we told you in confidence." Boulet said, sounding nervous.

"I shall. We both will." I assured him, and he visibly relaxed.

Allerton showed us to the door and hesitated before tentatively extending his hand. I thought he was uncertain as to whether I'd shake hands with him, but I did so. "I hope you find your murderer, Captain Hastings." He said.

"Thank you. I hope so too." Miss Lemon exchanged a goodbye with him, and we left.

When the door was closed behind us I gave a sigh. We knew a bit more, but were still no nearer to finding Poirot's killer as far as I could see. I needed to think about things, and when I glanced at my watch I realised it was later than I thought; probably too late to ask Miss Lemon to accompany me back to Poirot's flat to discuss the case.

"Can I drive you back home, Miss Lemon?" I asked her.

She looked at me and said, almost hesitantly, "I was planning on having fish for dinner, Captain Hastings, and it's a rather large piece of sole. I'm sure I could stretch it to both of us if you'd like to stay."

I gazed at her in silence for a couple of seconds. I'm sure she remembered what had occurred the last time I'd been at her flat as well as I did – I had a sudden memory of how her skin had felt, exquisitely soft and smooth under my hands and was sure I flushed. "I'd like that, Miss Lemon." I said, and was pleased to see her return my smile with one of her own.

Unlike Poirot, who never let me do anything in the kitchen apart from making the occasional cup of tea or washing up, Miss Lemon seemed quite happy to delegate the tasks involved with cooking. When I asked if I could help she gave me the job of peeling and dicing some vegetables while she attended to some of the more difficult chores, such as making a sauce for the meal.

By unspoken agreement we didn't speak much about the case until we were finishing the meal. Miss Lemon gave me a curious look, and finally asked "How did you work out the relationship between those two young men so quickly, Captain Hastings? I have to admit I wouldn't have thought of it."

I took a sip of wine before replying "You forget I went to public school, Miss Lemon; that sort of behaviour was… pretty widespread. I think at one time it was nicknamed 'the Eton disease.'" I grimaced slightly at my words. "We had stories of some masters to avoid and some older boys that it'd be best not to fag for. I was lucky, I was never sporty enough or pretty enough to attract anyone's interest. The worst thing I had to do was clear Johnson's rugby boots after matches."

Miss Lemon had been listening with grave attention. "What about the two men you knew in the war?"

"Oh, Jones and Wells." I managed to smile at the memory. "I found out about them by accident. They were in an empty dugout and I, em, overheard…" I found myself flushing as I spoke. "Anyway, I had a quiet word with them and told them to be a bit more discreet. If they'd been discovered by someone else they would've been flung out straight away. They may even have been court-martialled."

"So why didn't you report them?" Miss Lemon asked.

I shrugged, thinking of a way to explain my feelings to her. "It seemed so stupid, Miss Lemon." I said at last. "Plenty of the men visited the brothels every time they could, or would pay local women-" I trailed off, embarrassed to be saying such things in front of Miss Lemon.

"I understand, Captain Hastings. Things are different in wartime," she said, an almost wistful note in her voice.

Her words made me wonder briefly if Miss Lemon had ever had a brief fling during the war, but I quashed the thought and picked up the threads of my story. "Well, the soldiers that used the brothels, some even fell in love and become engaged to the women they met, and no one minded. Jones and Wells had found each other rather than a woman, but they might have been punished for it…" I shook my head. "It just didn't seem right to me. I know we're taught those sort of men are unnatural or perverted, but they weren't. They were good, brave lads. It made me realise there was nothing wrong with men with those sorts of desires." I paused. "Or do you think I should've reported them?"

"No, certainly not. I'm glad you didn't." Miss Lemon said, her tone rather stern, but her eyes showing a cool compassion. "I know that may not be a widespread view, but I think on the whole I agree with you."

I gave her a smile at that. I was relieved that we seemed to feel the same on the matter. I reflected that it could have made things difficult if she had felt differently.

"What happened to them?" She asked. "Did they survive the war?"

"Oh yes, even though Wells lost most of his right foot, poor chap. They both made it to the end of the war alive and still together. I received a Christmas card from them back in '22. They'd moved in with one of Wells' sisters. Apparently she thought it was perfectly acceptable for them to be in love and they were all happy living together."

"I'm glad. It's nice for people to have happy endings."

"Yes." I sighed. "However, as for Allerton and Boulet…"

"What do you think we should do next, Captain Hastings?" Miss Lemon asked.

"I'm not sure." I said truthfully. I pulled the letters Allerton had given me out of my pocket. The address they'd been instructed to send the blackmail material to was an ordinary shop in London, I was guessing the usual sort of small tobacconists and newsagents with basic post office facilities. There was no name, just a number, probably the number of a post office box where mail could be stored until the recipient had the time to collect it. Even if we went to the post office, there was no reason why the proprietor should reveal who had hired the box; in fact, they were probably bound by confidentiality not to.

"I think Allerton's blackmailer is Poirot's murderer, or at least hired them." I said. Again something about that nagged at me, and I frowned, trying to think why that should be.

"That seems likely." Miss Lemon agreed.

"But all we have is the number of a PO box, and we're unlikely to find out who opened the account for it."

"Japp could," Miss Lemon said, and then, "but – we can't tell him, can we?"

"That's the problem." I agreed. Japp, with the authority of the police, could demand to know everything about that particular branch's post office boxes, but to reveal our information to him we'd expose Boulet and Allerton's relationship, and even if by some miracle Allerton avoided prison (and I couldn't see that happening), the resulting scandal would destroy his personal reputation, and Boulet would be extradited, if not arrested for stealing confidential documents. "It's a mess, isn't it?" I concluded.

"It is." Miss Lemon agreed sadly. She reached across the table and laid her hand on mine in a gesture reminiscent of when I'd told her I'd find the people who'd murdered Poirot. "You'll think of something. We've got this far," she said with a gentle smile that was more encouraging then any morale-boosting speeches could've been.

I smiled, gently squeezing her hand. "Thanks, Felicity." I said without thinking, and then flinched. "Sorry, I didn't mean-" I began hastily.

"It's fine." She got to her feet and reached across to take my plate. "After all this time, I'm hardly likely to take offence at you calling me by my first name." She gave me a smile that I would've called impish on another woman. "And we're not in the office right now, Arthur."

"Thank goodness." I drained the last of my wine and got to my own feet as she moved to the sink. "I'll give you a hand with the dishes."