With Helen ready to enact her plan, the team is locked in a race against time to stop her.
- Been There, Shaped History: It's revealed that Helen killed the family of Australopithecus at AL 333
. - Cliffhanger: The episode ends with Abby and Connor stuck in the Cretaceous, and Danny stuck in the Pliocene, with no way to return to the present. Becker and Sarah, though, have some kind of plan to rescue them.
- Kill All Humans: It becomes apparent that this is Helen's plan. How she goes about achieving it, though, is unlike anything ever done in fiction: she goes back in time and tries to kill of the earliest hominids, preventing humans from evolving in the first place.
- Mythology Gag: After a raptor kills Helen by knocking her off a cliff (which ends up killng it too), Danny tells its corpse "good boy". Lester said the same thing to the mammoth in Season 2 after it saved him from a future predator.
- Oh, Crap!: Danny, Abbey and Connor have this reaction when they realize what Helen's plan is.
- Villainous Rescue: Just as Helen is about to kill Danny, a raptor attacks her, sending both over the cliff to their deaths.
