An English anthropologist has discovered a frozen monster in the frozen wastes of Manchuria which he believes may be the Missing Link. He brings the creature back to Europe aboard a trans-Siberian express, but during the trip the monster thaws out and starts to butcher the passengers one by one.—Jonathon Dabell
Christopher Lee, Peter Cushing, Alberto de Mendoza
IMDB plot
While on the Trans-Siberian Express, an anthropologist and his rival must contain the threat posed by the former's cargo: a prehistoric ape which is the host for a parasitic life-form.