The episode begins with Niko Tatopoulos and Elsie Chapman watching a report from Scotland detailing an alleged attack by The Loch Ness Monster. Nick believes it to be a hoax, but Elsie believes it warrants investigation. The two begin to debate this, and the rest of the group decide to pay the lake a visit. They first go to the institution that was damages by the attack, where Nick, Elsie, and Monique Dupre secure photos and references on the creature while Randy and Mendel visit a Nessie museum in town. When they return, The group descends into the lake with an institute official. Nick and Randy see the Monster and break away from the other submarine to chase it. They find it, but it destroys the glass on their vessel, so they are forced to swim out. Nick finds an Oxygen tank, but Randy is caught in some seaweed. Nick saves Randy, but Nessie surfaces with them. It begins to chase H.E.A.T., but Zilla Junior comes to save them. They discuss with the institute scientists the possibility of studying Nessie, but all they want to do is destroy it. Mendel soon sends N.I.G.E.L. to see where Nessis is. Back in the Laboratory, It is discovered that the institute has Nessis's offspring captive. Out on the water, Nessie creates a whirlpool that begins to suck H.E.A.T.'s boat down but it is saved by the quick thinking of Monique, who cuts the line to N.I.G.E.L. with a fire axe.Inside, Nick broadcasts the young Nessie's cries out into the water, which attracts its mother. Zilla Junior surfaces to fight the sea-serpent, but nessie quickly forgets about him when the Institute leader tries to flee to get the infant to the black market, but he is overpowered by its mother. His submarine is flung into the Lake, and Zilla Junior opens baby Nessie's cage as a show of peace. The group analyzes this behavior and the episode comes to an end,.
"It's all a scam! If your name was 'Schwarzenegger' they'd say you were 'McSchwarzenegger'!"
— Randy tries to convince Mendel against his belief of being a "McCraven"
This is the first episode to end with a comradery between monsters.
Elsie claims that Nessie is actually a "mosasaur", even though it more closely resembles a snake or an eel. Furthermore, Nick calls it a dinosaur: in reality mosasaurs were in fact aquatic lizards, relatives of the Komodo Dragon.
The plot is similar to Gorgo, where a young monster is held captive and its mother goes on a rampage.