An ex-detective goes undercover to find out the identity of a notorious informer who betrays his criminal associates to the police for his own gain.
Wallace adapted the novel into a play in 1928.
Adapted into a british film in 1930, screenplay by Edgar Wallace who also directed.
Adapted into a German film, titled Der Zinker, in 1931.
Another british film, based partly on the novel and partly the play, premiered in 1937, the screenplay was written by Wallace's eldest son Bryan.
Adapted into a German film, titled Der Zinker, in 1963.
A 1959 live TV film (also titled Der Zinker), which was made for East German television and is considered lost, was most likely based on the play, although some sources credit the novel.
