Carr, John Dickson - The Problem of the Green Capsule / The Black Spectacles (1939)

Review by Nick Fuller

5/5

"We are travelling in a house of illusions, a box of tricks, a particularly devious sort of ghost-train."

Carr's version of Agatha Christie's Cards on the Table, and, like that book, as brilliantly tricky a detective story as the reader could wish for. The rich dilettante Marcus Chesney uses a psychological observation test to demonstrate the method used to poison several children, the revelation of which trick would clear Marjorie Wills, his niece, from suspicion. She - and two other people - were watching Chesney's on-stage murder, in full view of each other; and Chesney's brother, the only other possible suspect, has a cast-iron alibi. Nobody could have committed the crime -yet it was committed. This is the authentic Carr touch, and the solution is typical of 1930s Carr: utterly brilliant, utterly surprising, and utterly convincing.