Fiftieth in the mystery series with Inspector Arnold and amateur detective Desmond Merrion.

Sir Phineas Barnsdale was that extraordinary being, an inventor who had made money: and it was his money that killed him. If he had not had a penny to bless himself with, he would never have met with that fatal injury from a blow on the head with an iron bar. The broad motives for the crime seemed evident from the first; it was the question of who had the opportunity and, more important, the time, that was to vex the minds of Inspector Amold of Scotland Yard and his talented friend Desmond Merrion. Time is of the essence and never has the phrase proved more a truism than in this ingenious detective story, where a sense of timing, and a meticulous regard for time itself, play such important parts.