“Dear Mr. Carter,

“Something’s turned up that has given me a jar.  Of course I may be simply making an awful ass of myself, but I don’t think so.  If my conclusions are right, that girl at Manchester was just a plant.  The whole thing was prearranged, sham packet and all, with the object of making us think the game was up—­therefore I fancy that we must have been pretty hot on the scent.

“I think I know who the real Jane Finn is, and I’ve even got an idea where the papers are.  That last’s only a guess, of course, but I’ve a sort of feeling it’ll turn out right.  Anyhow, I enclose it in a sealed envelope for what it’s worth.  I’m going to ask you not to open it until the very last moment, midnight on the 28th, in fact.  You’ll understand why in a minute.  You see, I’ve figured it out that those things of Tuppence’s are a plant too, and she’s no more drowned than I am.  The way I reason is this:  as a last chance they’ll let Jane Finn escape in the hope that she’s been shamming this memory stunt, and that once she thinks she’s free she’ll go right away to the cache.  Of course it’s an awful risk for them to take, because she knows all about them—­but they’re pretty desperate to get hold of that treaty.  But if they know that the papers have been recovered by us, neither of those two girls’ lives will be worth an hour’s purchase.  I must try and get hold of Tuppence before Jane escapes.

“I want a repeat of that telegram that was sent to Tuppence at the Ritz.  Sir James Peel Edgerton said you would be able to manage that for me.  He’s frightfully clever.

“One last thing—­please have that house in Soho watched day and
night. 
    “Yours, etc.,
    “Thomas Beresford.”

The Prime Minister looked up.

“The enclosure?”

Mr. Carter smiled dryly.

“In the vaults of the Bank.  I am taking no chances.”

“You don’t think”—­the Prime Minister hesitated a minute—­“that it would be better to open it now?  Surely we ought to secure the document, that is, provided the young man’s guess turns out to be correct, at once.  We can keep the fact of having done so quite secret.”

“Can we?  I’m not so sure.  There are spies all round us.  Once it’s known I wouldn’t give that”—­he snapped his fingers—­“for the life of those two girls.  No, the boy trusted me, and I shan’t let him down.”

“Well, well, we must leave it at that, then.  What’s he like, this lad?”

“Outwardly, he’s an ordinary clean-limbed, rather block-headed young Englishman.  Slow in his mental processes.  On the other hand, it’s quite impossible to lead him astray through his imagination.  He hasn’t got any—­so he’s difficult to deceive.  He worries things out slowly, and once he’s got hold of anything he doesn’t let go.  The little lady’s quite different.  More intuition and less common sense.  They make a pretty pair working together.  Pace and stamina.”