While on an inter-galactic pizza run, Ratchet and Clank discover that the diabolical Dr. Nefarious has developed an interdimensional portal device that would allow him to rule the entire multiverse. The intrepid duo spring into action, liberating the "Portalizer" from Dr. Nefarious and then racing off to securely lock it away in a weapons museum. But along the way, they run into bumbling Captain Qwark, who uses the weapon to accidentally unleash a sentient-pizza-topping mob upon the citizens of Galactic City. It's up to Ratchet and Clank to battle the savory horde and keep the Portalizer out of Dr. Nefarious' evil hands before he uses it to destroy the galaxy.