When a nuclear submarine encounters an anomaly in the North Sea, the team is brought aboard to help close it. The team have to deal with a dinosaur inside the sub, and a pod of marine reptiles outside.

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* FromBadToWorse: And how! First, the theropod dinosaur wakes up and starts killing crewmembers. Then, the sub is attacked by a Liopleurodon, knocking out the captain, and disabling the ability to steer, ''then'', the sub gets sucked into the anomaly where a whole pod of Liopleurodons are waiting. Think it can't get any worse? '''Then''' the irate admiral orders a nuke to be fired at the anomaly, threatening to drastically alter the timeline should it go off in the Jurassic. It's certainly never a dull day for the ARC team.
* InformedSpecies: Official material claims that the swimming theropod is a ''Eustreptospondylus'', despite the creature itself looking more like a raptor of some kind.
* JerkassHasAPoint: While nuking the past is certainly the wrong way to fix the problem, the Admiral isn't wrong that if another country's sub were to disappear through the anomaly, it's almost certain that they'll place the blame on the United Kingdom.
* ObstructiveBureaucrat: Against Lester's urging, the Minister goes ahead with the Admiral's plan to fire a nuclear missile at the anomaly.
* ScientistVsSoldier: A version of this happens after the submarine gets pulled through the anomaly. The Admiral thinks they can get rid of the anomaly by hitting it with a nuke. While Lester isn't a scientist, he rightfully argues that setting off a nuke in prehistoric times could end the world as they know it.