After mysterious lights appear over Cooper Hill, apparent location for several UFO sightings, forest ranger Felicity Ford is found dead and wrapped in black ooze. Ufologists arrive in the area for tours run by enterprising Abigail Tonev, and Barnaby learns that one of them, Carter Faulkner, had a run-in with Felicity over parking his trailer in the woods. Before she died, she had tried to ring her father, a group captain at a radar station - who denies receiving any call - and she was also having an affair behind her boyfriend's back. The idea of extraterrestrials seems credible when Abigail has a close encounter of the third kind but following two more slayings, Barnaby is able to provide an earthly solution to the incident at Cooper Hill.
—don @ minifie-1