'As a little favour, may I examine the flat below?' 'Why, certainly, M. Poirot. I know what they think of you at headquarters. I'll leave you a key. I've got two. It will be empty.

The maid cleared out to some relatives, too scared to stay there

'I thank you,' said M. Poirot. He went back into the flat, thoughtful.

'You're not satisfied, M. Poirot?' said Jimmy.

'No,' said Poirot. 'I am not satisfied.' Donovan looked at him curiously. 'What is it that - well, worries you?' Poirot did not answer. He remained silent for a minute or two, frowning, as though in thought, then he made a sudden impatient movement of shoulders.

'I will say good night to you, mademoiselle. You must be tired You have had much cooking to do - eh?' Pat laughed. 'Only the omelette. I didn't do dinner. Donova and Jimmy came and called for us, and we went out to a littl place in Soho.' 'And then without doubt, you went to a theatre?' 'Yes. The Brown Eyes of Caroline.' 'Ahl' said Poirot. 'It should have been blue eyes - the blue eye: of mademoiselle.' He made a sentimental gesture, and then once more wished Pa good night, also Mildred, who was staying the night by special request, as Pat admitted frankly that she would get the horrors, if left alone on this particular night.

The two young men accompanied Poirot. When the door wa., shut, and they were preparing to say goodbye to him on th{landing, Poirot forestalled them.

'My young friends, you heard me say that I was not satisfiedl Eh bien, it is true - I am not. I go now to make some little investiga. tions of my own. You would like to accompany me - yes?' An eager assent greeted this proposal. Poirot led the way to th flat below and inserted the key the inspector had given him in th4 lock. On entering, he did not, as the others had expected, ente the sitting-room. Instead he went straight to the kitchen. In a litth recess which served as a scullery a big iron bin was standing.

Poirot uncovered this and, doubling himself up, began to rootk in it with the energy of a ferocious terrier.

Both Jimmy and Donovan stared at him in amazement.

Suddenly with a cry of triumph he emerged. In his hand he held aloft a small stoppered bottle.

'Voild!' he said. 'I find what I seek.' He sniffed at it delicately.

'Alas! I am enrhurad - I have the cold in the head.' Donovan took the bottle from him and sniffed in his turn, bm could smell nothing. He took out the stopper and held the bottk to his nose before Poirot's warning cry could stop him.

Immediately he fell like a log. Poirot, by springing forward: partly broke his fall.

'Imbecile!' he cried. 'The idea. To remove the stopper in that foolhardy mannerl Did he not observe how delicately I handled it? Monsieur - Faulkener - is it not? Will you be so good as to get me a little brandy? I observed a decanter in the sitting-room.'

Jimmy hurried off, but by the time he returned, Donovan was sitting up and declaring himself quite all right again. He had to listen to a short lecture from Poirot on the necessity of caution in sniffmg at possibly poisonous substances.

'I think I'll be off home,' said Donovan, rising shakily to his feet. 'That is, if I can't be any more use here. I feel a bit wonky still.'

'Assuredly,' said Poirot. 'That is the best thing you can do.

M. Faulkener, attend me here a little minute. I will return on the instant.'

He accompanied Donovan to the door and beyond. They remained outside on the landing talking for some minutes When Poirot at last re-entered the flat he found Jimmy standing in the sitting-rom gazing round him with puzzled eyes.

'Well, M. Poirot,' he said, 'what next?' 'There is nothing next. The case is finished.' 'What?'

'I know everything - now.'

Jimmy stared at him. 'That little bottle you found?'

'Exactly. That little bottle.'

Jimmy shook his head. 'I can't make head or tail of it. For some reason or other I can see you are dissatisfied with the evidence against this John Fraser, whoever he may be.'

'Whoever he may be,' repeated Poirot softly. 'If he is anyone at all - well, I shall be surprised.'

'I don't understand.'

'He is a name - that is all - a name carefully marked on a handkerchiefl'

'And the letter?'

'Did you notice that it was printed? Now, why? I will tell you.

Handwriting might be recognized, and a typewritten letter ia more easily traced than you would imagine - but if a real John Fraser wrote that letter those two points would not have appealed to himl No, it was written on purpose, and put in the dead woman's pocket for us to find. There is no such person as John Fraser.' Jimmy looked at him inquiringly.

'And so,' went on Poirot, 'I went back to the point that first struck me. You heard me say that certain things in a room were always in the same place under given circumstances. I gave three instances. I might have mentioned a fourth - the electric-light switch, my friend.' Jinuny still stared uncomprehendingly. Poirot went on.

'Your friend Donovan did not go near the window - it was by resting his hand on this table that he got it covered in bloodl But I asked myself at once - why did he rest it there? What was he doing groping about this room in darkness? For remember, my friend, the electric-light switch is always in the same place - by the door. Why, when he came to this room, did he not at once feel for the light and turn it on? That was the natural, the normal thing to do. According to him, he tried to turn on the light in the kitchen, but failed. Yet when I tried the switch it was in perfect working order. Did he, then, not wish the light to go on just then? If it had gone on you would both have seen at once that you were in the wrong flat. There would have been no reason to come into this room.' 'What are you driving at, M. Poirot? I don't understand. What do you mean?' 'I mean - this.' Poirot held up a Yale door key.

'The key of this flat?' 'N0, mon ami, the key of the flat above. Mademoiselle Patricia's key, which M. Donovan Bailey abstracted from her bag some time during the evening.' 'But why - why?' 'Parbleul So that he could do what he wanted to do - gain admission to this flat in a perfectly unsuspicious manner. He made sure that the lift door was unbolted earlier in the evening.' 'Where did you get the key?' P0irot's smile broadened. 'I found it just now - where I looked for it- in M. Donovan's pocket. See you, that little bottle I pretended to find was a ruse. M. Donovan is taken in. He doe

what I knew he would do - unstoppers it and sniffs. And in that little bottle is ethyl chloride, a very powerful instant anaesthetic.

It gives me just the moment or two of unconsciousness I need. I take from his pocket the two things that I knew would be there.

This key was one of them - the other ' He stopped and then went on.

'I questioned at the time the reason the inspector gave for the body being concealed behind the curtain. To gain time? No, there was more than that. And so I thought of just one thing the post, my friend. The evening post that comes at half past nine or thereabouts. Say the murderer does not find something he expects to find, but that something may be delivered by post later.

Clearly, then, he must come back. But the crime must not be discovered by the maid when she comes in, or the police would take possession of the flat, so he hides the body behind the curtain.

And the maid suspects nothing and lays the letters on the table as usual.' 'The letters?' 'Yes, the letters.' Poirot drew something from his pocket. 'This is the second article I took from M. Donovan when he was unconscious.' He showed the superscription - a typewritten envelope addressed to Mrs Ernestine Grant. 'But I will ask you one thing first, M. Faulkener, before we look at the contents of this letter. Are you or are you not in love with Mademoiselle Patricia?' 'I care for Pat damnably - but I've never thought I had a chance.' 'You thought that she cared for M. Donovan? It may be that she had begun to care for him - but it was only a beginning, my friend. It is for you to make her forget - to stand by her in her trouble.' 'Trouble?' said Jimmy sharply.