James Answell is paying a visit to his future father-in-law, the champion archer Avory Hume, at his Grosvenor Street townhouse. Invited into the study and offered a drink, Answell suddenly swoons - and awakes to find the door and windows locked from the inside. His host is dead, skewered with an arrow, and Answell is the prime suspect. The devilish puzzle constructed, Carter Dickson unravels an ingenious courtroom thriller, in which the razor-sharp amateur detective Sir Henry Merrivale argues for the defence in all of his outlandish glory - and the mystery of the 'Judas Window' is unveiled.