With the ABC killer still on the loose, Hercule realises that only he holds the key to the murders. He faces a race against time to stop the bloodbath.
1933. Hercule Poirot, older and greyer, receives letters threatening murder. The sender signs themselves only as “A.B.C.” When he takes the letters to the police looking for help, Hercule finds all his old friends have moved on. But soon there is a murder and the once-great detective must take matters into his own hands.