A thriller serial in six parts by Bill Craig
starring William Lucas as Eddie Prior, Claire Nielson as Liz Elliot, Peter Copley as Cadwaller, Aubrey Morris as Spinner and Callum Mill as Sgt. Forbes
From Scotland

With Cadwaller at the cottage, Liz searches his room and discovers a picture of Helen. Eddie, awake in the dark hours of the night, goes outside to investigate the arrival of a van and finds Dewar's boat unloading a furtive cargo at the old quay.
Next morning, in Dewar's garage, Eddie discovers a lifebelt from the lost motorboat. An angler's sea-hook is embedded in it. He takes it to Spinner who confirms its similarity to the one with which he hooked the drowned man. But as Eddie is driving back with his evidence...