S1·E20 The Sentry

The government is keen to hush up a series of mysterious deaths at the Merrymount Institute, an underground archival facility. When Carl investigates, he determines that the victims were ripped apart as if attacked by a crocodile or other large lizard. He eventually discovers that the workers excavated a series of strange egg-like objects, and that the eggs' mother, a large prehistoric lizard, is attempting to retrieve them. Fleeing for his life, Carl must return the eggs to the mother and fend her off.