After a storm wrecks the Aquarium tide-pool's research lab, Grant Roberts (Donnelly Rhodes) takes Nicole's (Ocean Hellman) science class to the tide-pool lab to gather new data.

A BC Hydro crew finds an intact fossil of a fish with legs. When Grant learns of the discovery he thinks the animal could be the "missing link" in the evolutionary chain. Grant takes Jonah and his friend Martin on a trip to study the fossil. Martin's father Don is a famous biologist who also joins the crew. The expedition proves to be an opportunity to study the distant past and for an estranged father and son (Don and Martin) to renew their relationship.