Revenge has many shapes. In the game of espionage the shape is usually death. But there is another kind of death - that of the mind. When a man wakes to find he cannot tell nightmare from reality, he is on the road to Limbo, at the frontier of Hell. Jonathan Blake realised he was on that road when he could no longer tell whether the nurse bending over him with the needle was a sister of mercy or his murderer...
Used availability for John Newton Chance's A Bad Dream of Death
November 1972 : UK Hardback
December 2000 : UK Paperback