"David" (David Naughton) and his pal "Jack" (Griffin Dunne) are taking a walking tour of the UK when they decide to stop off at a pub. They are about as welcome as a dose of the clap and after a few minutes banter with the natives decide they are better off walking. The thing is, those inside know how dangerous it's about to be out there - and the boys soon find out. It's "David" who wakes up in hospital, replete with some mysterious scratch marks, nightmares and claiming that they were attacked by a brutal hound. Nobody really believes him, and anyway his attention is quickly diverted by nurse "Alex" (Jenny Agutter) whom he visits for dinner and never leaves. Luckily she works nights, else she might have discovered that her beau doesn't just stop at a bit of gentle biting. With corpses piling up around London, he is at a loss to know where he goes at night (waking up naked in the wolf enclosure at the zoo might be the final straw) but try as he might, he can't engage the authorities with his claims. Maybe only doctor "Hirsch" (John Woodvine) believes that something unusual is amiss - but can he help before "David" does himself or anyone else more damage! Increasingly more often naked as he goes along, Naughton joins in with the spirit of this enjoyable comedy horror with enthusiasm. I wonder what might happen now if a naked man in a bush even mentioned a boy's balloons!? It runs out of steam a little at the end, and Agutter's acting never really evolved much from the "Railway Children" 1970) but the visual effects work quite well especially when the full moon rises!