The brutal murder of a woman in a lonely beach cottage, huge footprints found nearby, a meandering tramp singing snatches of opera in the night! Superintendent Minter - "Sooper", rattles around the countryside on his noisy motorbike and tries to find a connection. Hampered by amateur detective Gordon Cardew, aided and admired by lawyer Jim Ferraby and the beautiful Elfa Leigh, Sooper finds the case further complicated by another murder. The mysterious `Big Foot' anticipates Minter's every move and only by delving into the past does he solve the case and bring the villain to justice.