On his return to Geneva, Brian Innes must meet Audrey Page and find a way to prevent her from joining the strangely temperamental group of people gathered around film star Eve Eden at the Villa Rosalind. With characteristic stubbornness, if not trusting naivety, she refuses to be detained and is immediately encircled by terror, while the jaws of a murder trap swing closed.
Fortunately, Dr Gideon Fell is on hand, and when the murderer strikes with an invisible weapon, Fell accepts the challenge with brilliance and wit.

John Dickson Carr, the master of the locked-room mystery, was born in Uniontown, Pennsylvania, the son of a US Congressman. He studied law in Paris before settling in England where he married an Englishwoman, and he spent most of his writing career living in Great Britain. Widely regarded as one of the greatest Golden Age mystery writers, his work featured apparently impossible crimes often with seemingly supernatural elements. He modelled his affable and eccentric series detective Gideon Fell on G. K. Chesterton, and wrote a number of novels and short stories, including his series featuring Henry Merrivale, under the pseudonym Carter Dickson. He was one of only two Americans admitted to the British Detection club, and was highly praised by other mystery writers. Dorothy L. Sayers said of him that 'he can create atmosphere with an adjective, alarm with allusion, or delight with a rollicking absurdity'. In 1950 he was awarded the first of two prestigious Edgar Awards by the Mystery Writers of America, and was presented with their Grand Master Award in 1963. He died in Greenville, South Carolina in 1977.