Lighthearted British aviation suspense, conventionally plotted but textured with bright dialogue and air-borne expertise. Seamus Squire, a naval security officer who's been working on a supersecret, remote-controlled atomic sub, goes off to the Highlands to enjoy his new Teal Amphibian aircraft and set up housekeeping in a lonely cottage on a loch--where mysterious things start happening (including the drowning of an enigmatic visitor). So soon, along with new neighbor Cloudy McNeil, Seamus is back to work for security, picking up jet-pilot Jack Plumley and bringing him back to base in the Teal. What's going on? Well, the unmanned sub has gone out of control and can't be approached by anything bearing a motor (or it will self-destruct). And Jack gives Seamus a ride in his Phantom jet out to the aircraft carrier where the investigation of the loose sub is to ensue. Meanwhile, Cloudy is kidnapped by Soviet spies; Seamus' seaplane is crippled when he rescues her; and the plane floats to the lost sub, which he boards. In sum: nothing unusual, but amusingly told.