All the surviving dinosaurs of the time crossed over into this new realm. Sixty-five million years ago, a meteorite crashed into the Earth and in doing so ripped the universe into two parallel dimensions. They find themselves in a strange dystopian parallel world where a human-like race evolved from dinosaurs rather than the mammalian ancestry of true humans in a Manhattan-like city. Mario and Luigi awaken a minute later and head deeper into the caves following Daisy's screams and discover an interdimensional portal through which Mario and Luigi follow Daisy. The three go back to the flooding and the brothers manage to fix it but are knocked out by two strange characters, Iggy and Spike, who proceed to kidnap Daisy.
They rush back to his apartment where they inform Mario about the incident. Luigi tries to stop it but he does not have his tools on him so he cannot fix it. After a date, she takes Luigi to the dig and witnesses Scapelli's men (who, along with Scapelli himself, had previously threatened her to end her research on that specific piece of land for their own interests) sabotage it by leaving the water-pipes open.
Luigi falls in love with an orphaned NYU student, Daisy, who is digging under the Brooklyn Bridge for dinosaur bones. The brothers are being driven out of business by the mafia-like Scapelli Construction Company, led by contractor Anthony Scapelli. Mario and Luigi are two Italian American plumbers living in Brooklyn.