When Blore returned from the house with a rope coiled over his arm, he found Armstrong where he had left him staring down into the depths.

Blore said breathlessly: «Where’s Mr. Lombard?»

Armstrong said carelessly: «Gone to test some theory or other. He’ll be back in a minute. Look here, Blore, I’m worried.»

«I should say we were all worried.»

The doctor waved an impatient hand.

«Of course – of course. I don’t mean it that way. I’m thinking of old Macarthur.»

«What about him, sir?»

Dr. Armstrong said grimly: «What we’re looking for is a madman. What price Macarthur?»

Blore said incredulously: «You mean he’s homicidal?»

Armstrong said doubtfully:

«I shouldn’t have said so. Not for a minute. But of course I’m not a specialist in mental diseases. I haven’t really had any conversation with him – I haven’t studied him from that point of view.»

Blore said doubtfully:

«Ga ga, yes! But I wouldn’t have said —»

Armstrong cut in with a slight effort as of a man who pulls himself together.

«You’re probably right! Damn it all, there must be some one hiding on the island! Ah! here comes Lombard.»

They fastened the rope carefully.

Lombard said: «I’ll help myself all I can. Keep a lookout for a sudden strain on the rope,»

After a minute or two, while they stood together watching Lombard’s progress, Blore said:

«Climbs like a cat, doesn’t he?»

There was something odd in his voice.

Dr. Armstrong said: «I should think he must have done some mountaineering in his time.»

«Maybe.»

There was a silence and the ex-Inspector said:

«Funny sort of cove altogether. D’you know what I think?»

«What?»

Hes a wrong un!

Armstrong said doubtfully: «In what way?»

Blore grunted. Then he said:

«I don’t know – exactly. But I wouldn’t trust him a yard.»

Dr. Armstrong said; «I suppose he’s led an adventurous life.»

Blore said: «I bet some of his adventures have had to be kept pretty dark.» He paused and then went on: «Did you happen to bring a revolver along with you, doctor?»

Armstrong stared.

«Me? Good Lord, no. Why should I?»

Blore said: «Why did Mr. Lombard?»

Armstrong said doubtfully: «I suppose – habit.»

Blore snorted.

A sudden pull came on the rope. For some moments they had their hands full. Presently, when the strain relaxed, Blore said:

«There are habits and habits! Mr. Lombard takes a revolver to out-of-the-way places, right enough, and a primus and a sleeping bag and a supply of bug powder, no doubt! But habit wouldn’t make him bring the whole outfit down here! It’s only in books people carry revolvers around as a matter of course,»

Dr. Armstrong shook his head perplexedly.

They leaned over and watched Lombard’s progress. His search was thorough and they could see at once that it was futile. Presently he came up over the edge of the cliff. He wiped the perspiration from his forehead.

«Well,» he said. «We’re up against it. It’s the house or nowhere.»