Professor Bacterio has invented a new machine (the "Telefrusky") that allows travel to the world of cinema, and he decides that Mortadelo and Filemón should travel to "Jurassic Park" and bring back samples of dinosaur DNA to return Ofelia to her natural size after she was reduced to a minimal size by trying a slimming elixir also created by Bacterio (of course!).

Thus, the agents are mistakenly transported to a town in the American West called Western City, which has it all: the sheriff, the saloon, the gallows, the Indians... The contraption will then transport them to the world of horror films, but they have the misfortune of it breaking down, risking being stuck in this alternate reality forever. The only person who can help them is a crazy and enigmatic professor named Ibáñezstein, who will make a deal with them: he will repair their machine only if the agents are willing to travel through the most famous horror movies and get him the necessary elements to create his peculiar creature. Will they manage to reach the world of dinosaurs?

Extended version with alternate passages combining 'Dos vaqueros chapuceros' and 'Terror, Espanto y Pavor'. Local network multiplayer option.

Classic point & click adventure where you can control either Mortadelo or Filemón according to your preference: switch characters and choose who will perform each action.