The Judas Window

Blurb

The Judas Window is a famous locked room mystery novel by the American writer John Dickson Carr, writing under the name of Carter Dickson, published in 1938 and featuring detective Sir Henry Merrivale.
In a poll of 17 mystery writers and reviewers, this novel was voted as the fifth best locked room mystery of all time. The Hollow Man also by John Dickson Carr was voted the best.