Amy Pond, while outside the Doctor's TARDIS, gets infected with a Chronic Spasm Virus. The virus causes her to jump randomly through time and space. The Eleventh Doctor and Rory track her by following her time trail, but are unable to reach her before she momentarily arrives in the trenches of France in 1917, Ancient Rome, the court of Queen Elizabeth the First and pre-historic Earth, where she is pursued by a tyrannosaurus rex and a predator bulge in the time vortex that threatens to swallow her up.