The letter! What was the explanation of the letter?
Was it not an argument of equal weight for Sisily's innocence, suggesting the existence of some hidden avenging figure glimpsed by Robert Turold in time to give him warning of his death, but not in time to enable him to avert it?
There were other things too.

What was the meaning of that sly and stealthy shake of the head which Austin Turold had given his son that afternoon.

A warning obviously--but a warning for what purpose?
Mr.Brimsdown could not guess, but his contemplation of the incident brought before him the image of the restless and unhappy young man, as he stood by the bedside in the next room, pointing to the marks on the dead man's arm.

Even in his vehement assertions of Sisily's innocence Mr.Brimsdown had conceived the impression that he was keeping something back.

What did Charles Turold know?
Did his father share his secret knowledge?
Mr.Brimsdown could not answer these questions, and he was greatly perturbed at the way in which they brought a host of other thoughts and doubts in their train.