At eleven o'clock he tidied up his papers and prepared to go to bed. Before doing do, he just glanced into his wife's room to make sure that there was nothing she wanted. He discovered the electric light on and his wife lying in bed stabbed through the heart. She had been dead at least an hour - probably longer. The following were the points made. There was another door in Mrs. Rhodes's room leading to the corridor. This door was locked and bolted on the inside. The only window in the room was closed and latched. According to Mr. Rhodes nobody had passed through the room in which he was sitting except a chambermaid bringing hot water bottles. The weapon found in the wound was a stiletto dagger which had been lying on Mrs. Rhodes's dressing-table. She was in the habit of using it as a paper knife. There were no fingerprints on it.

The situation boiled down to this - no one but Mr. Rhodes and the chambermaid had entered the victim's room. I inquired about the chambermaid. 'That was our first line of inquiry,' said Mr. Petherick. 'Mary Hill is a local woman. She has been chambermaid at the Crown for ten years. There seems absolutely no reason why she should commit a sudden assault on a guest. She is, in any case, extraordinarily stupid, almost half-witted. Her story has never varied. She brought Mrs. Rhodes her hot water bottle and says the lady was drowsy - just dropping off to sleep. Frankly, I cannot believe, and I am sure no jury would believe, that she committed the crime.'

Mr. Petherick went on to mention a few additional details. At the head of the staircase in the Crown Hotel is a kind of miniature lounge where people sometimes sit and have coffee. A passage goes off to the right and the last door in it is the door into the room occupied by Mr. Rhodes. The passage then turns sharply to the right again and the first door around the corner is the door into Mrs. Rhodes's room. As it happened, both these doors could be seen by witnesses.

The first door - that into Mr. Rhodes's room, which I will call A, could be seen by four people, two commercial travellers and an elderly married couple who were having coffee. According to them nobody went in or out of door A except Mr. Rhodes and the chambermaid. As to the other door in passage B, there was an electrician at work there and he also swears that nobody entered or left door B except the chambermaid.

It was certainly a very curious and interesting case. On the face of it, it looked as though Mr. Rhodes must have murdered his wife. But I could see that Mr. Petherick was quite convinced of his client's innocence and Mr. Petherick was a very shrewd man.

At the inquest Mr. Rhodes had told a hesitating and rambling story about some woman who had written threatening letters to his wife. His story, I gathered, had been unconvincing in the extreme. Appealed to by Mr. Petherick, he explained himself.

'Frankly,' he said, 'I never believed it. I thought Amy had made most of it up.'

Mrs. Rhodes, I gathered, was one of those romantic liars who go through life embroidering everything that happens to them. The amount of adventures that, according to her own account, happened to her in a year was simply incredible. If she slipped on a bit of banana peel it was a case of near escape from death. If a lamp-shade caught fire, she was rescued from a burning building at the hazard of her life. Her husband got into the habit of discounting her statements.

Her tale as to some woman whose child she had injured in a motor accident and who had vowed vengeance on her - well, Mr. Rhodes had simply not taken any notice of it. The incident had happened before he married his wife and although she had read him letters couched in crazy language, he had suspected her of composing them herself. She had actually done such a thing once or twice before. She was a woman of hysterical tendencies who craved ceaselessly for excitement.

Now, all that seemed to me very natural - indeed, we have a young woman in the village who does much the same thing. The danger with such people is that when anything at all extraordinary really does happen to them, nobody believes they are speaking the truth. It seemed to me that that was what had happened in this case. The police, I gathered, merely believed that Mr. Rhodes was making up this unconvincing tale in order to avert suspicion from himself.

I asked if there had been any women staying by themselves in the Hotel. It seems there were two - a Mrs. Granby, an Anglo-Indian widow, and a Miss Carruthers, rather a horsey spinster who dropped her g's. Mr. Petherick added that the most minute inquiries had failed to elicit anyone who had seen either of them near the scene of the crime and there was nothing to connect either of them with it in any way. I asked him to describe their personal appearance. He said that Mrs. Granby had reddish hair rather untidily done, was sallow-faced and about fifty years of age. Her clothes were rather picturesque, being made mostly of native silks, etc. Miss Carruthers was about forty, wore pince-nez, had close-cropped hair like a man and wore mannish coats and skirts.

'Dear me,' I said, 'that makes it very difficult.'

Mr. Petherick looked inquiringly at me, but I didn't want to say any more just then, so I asked what Sir Malcolm Olde had said.

Sir Malcolm Olde, it seemed, was going all out for suicide. Mr. Petherick said the medical evidence was dead against this, and there was the absence of fingerprints, but Sir Malcolm was confident of being able to call conflicting medical testimony and to suggest some way of getting over the fingerprint difficulty. I asked Mr. Rhodes what he thought and he said all doctors were fools but he himself couldn't really believe his wife had killed herself. 'She wasn't that kind of woman,' he said simply - and I believed him. Hysterical people don't usually commit suicide.

I thought a minute and then I asked if the door from Mrs. Rhodes's room led straight to the corridor. Mr. Rhodes said no - there was a little hallway with bathroom and lavatory. It was the door from the bedroom to the hallway that was locked and bolted on the inside.

'In that case,' I said, 'the whole thing seems to me remarkably simple.'

And really, you know, it did… The simplest thing in the world. And yet no one seemed to have seen it that way. Both Mr. Petherick and Mr. Rhodes were staring at me so that I felt quite embarrassed.

'Perhaps,' said Mr. Rhodes, 'Miss Marple hasn't quite appreciated the difficulties.'

'Yes,' I said, 'I think I have. There are four possibilities. Either Mrs. Rhodes was killed by her husband, or by the chambermaid, or she committed suicide, or she was killed by an outsider whom nobody saw enter or leave.'

'And that's impossible,' Mr. Rhodes broke in. 'Nobody could come in or go out through my room without my seeing them, and even if anyone did manage to come in through my wife's room without the electrician seeing them, how the devil could they get out again leaving the door locked and bolted on the inside?'

Mr. Petherick looked at me and said: 'Well, Miss Marple?' in an encouraging manner.

'I should like,' I said, 'to ask a question. Mr. Rhodes, what did the chambermaid look like?'

He said he wasn't sure - she was tallish, he thought - he didn't remember if she was fair or dark. I turned to Mr. Petherick and asked him the same question.

He said she was of medium height, had fairish hair and blue eyes and rather a high colour.

Mr. Rhodes said: 'You are a better observer than I am, Petherick.'

I ventured to disagree. I then asked Mr. Rhodes if he could describe the maid in my house. Neither he nor Mr. Petherick could do so.

'Don't you see what that means?' I said. 'You both came here full of your own affairs and the person who let you in was only a parlourmaid. The same applies to Mr. Rhodes at the Hotel. He saw only a chambermaid. He saw her uniform and her apron. He was engrossed by his work. But Mr. Petherick has interviewed the same woman in a different capacity. He has looked at her as a person.