Luck favoured him. For the letter that Mrs. Gertstein had written to Larry went to the latter’s Hampstead home. Now the Post Office is jealous of the sanctity of the mail⁠—even that of a crook⁠—and there could be no tampering with correspondence under official cognizance. There are more ways of killing a cat than one, however. Some of Labar’s men engaged on the task of watching the house had made themselves on good terms with the postmen. And so it was that a delivery bag was left unguarded for two minutes at a certain garden gate. Mrs. Gertstein’s letter was included in the next delivery at Larry’s house, but meanwhile Labar had become possessed of a copy of it.

He whistled a little jig air as he read. Here was a flood of light. Here also⁠—to vary the simile⁠—were muddy waters which it behoved him to stir carefully. Before he made any move it would be well to guard himself.

He went to see Marlow, the detective superintendent, who was his immediate chief. Marlow read the letter with impassive face.