He was, indeed, in an agony of diplomacy.

It was clear that Syme's inspired impudence was likely to bring him out of all merely accidental dilemmas.
Little was to be hoped from them.

He could not himself betray Syme, partly from honour, but partly also because, if he betrayed him and for some reason failed to destroy him, the Syme who escaped would be a Syme freed from all obligation of secrecy, a Syme who would simply walk to the nearest police station.

After all, it was only one night's discussion, and only one detective who would know of it.

He would let out as little as possible of their plans that night, and then let Syme go, and chance it.
He strode across to the group of anarchists, which was already distributing itself along the benches.
"I think it is time we began," he said; "the steam-tug is waiting on the river already.