When a submarine encounters an anomaly and a prehistoric creature out at sea, Matt, Abby and Connor are brought aboard to investigate. Their plans to contain the creature and seal the anomaly prove difficult, especially when the submarine loses power and is pulled through the anomaly to the seas of the Jurassic Period. With a young but dangerous theropod dinosaur aboard the submarine, the ARC team then work alongside its naval counterparts to restore power and return through the anomaly before it closes or before they are attacked by an oncoming pod of Liopleurodon. Back at the ARC, Lester and Jess have a battle of their own as they try and dissuade an admiral from nuking the anomaly. At the end of the episode Abby reveals to Matt what happened to Emily after she returned to the 19th century.