A Spanish resistance leader's safety in England is threatened by the passage through Parliament of the Aliens Extradition Bill. The minister responsible receives a message from four mysterious figures warning him to withdraw the legislation or face death. The suspense grows as the police struggle to protect the minister before the conspirators' deadline is reached; the ingenious final puzzle was to mark out Edgar Wallace as an outstanding writer of detective thrillers.

Included in this edition is his later novel, The Council of Justice, which forms a sequel.