In search of a new energy source, Russia accidentally reawakens the Kolossus - a giant robot doomsday device from the Cold War. At the same time, a new Mega Shark appears, threatening global security.

In the wake of the deadly confrontation between monster and metal in Mega Shark vs. Mecha Shark (2014), yet another Megalodon sees the light of day after the Russians' shady drilling operation for extremely potent crystals of red mercury. As a result, the gigantic Cold-War robot of mass destruction, Kolossus, wakes up from hibernation, while, elsewhere, Dr Alison Gray is struggling to come up with a way to contain the unstoppable underwater menace. Sooner or later, nature's most effective killer and man's deadliest creation will cross paths, and then, there's no telling what these two killing machines can do. Who shall live and who shall die after the final battle between Mega Shark and Kolossus?—Nick Riganas