Australian detective Scobie Malone is sent to England with an arrest warrant for an Australian citizen. The suspect, Sir James Quentin, is wanted in connection with an old murder. However, Quentin is currently acting as high commissioner for high-level international peace talks, and with the negotiations too sensitive to be disturbed, Malone ends up watching Quentin instead. It soon becomes apparent to the policeman that a plot is being hatched to bring the talks to an end, and that Quentin is very likely a target for assassination.