An alien craft lands in woodland near the home of horseman Russell Stone. When Stone goes missing suspicion initially falls on Ben Culley, a tramp with whom Stone had recently argued over trespassing on his property. However, Culley is found dead and it seems likely that the green alien who killed him has captured Stone.The trail leads to a nearby lake where it seems likely that the alien is hiding. . . Michael Jayston stars as Russell Stone. Also starring Ed Bishop, Dolores Mantez, and Susan Jameson.