When a number of locals report UFO sightings on the moor, Mike and Bellamy investigate and find the dead body of cyclist Paolo Ermini. Craddock thinks uncovering the truth about the UFO sightings will catch the killer, whilst Mike looks into Paolo's womanizing past. Meanwhile, Greengrass sells a load of garden gnomes. But later discovers they are Chairman Mao's. Trying to get rid of them, he recruits a young enthusiastic librarian to help him.