Dogmension

Plot
200,000 years ago, a meteorite crashes into the Earth, ending the reign of dogs and splitting the universe into two parallel dimensions. Half of all the world's dogs cross into a new dimension and evolve into a humanoid race.

In the present, a mysterious woman leaves a little sack, along with a bone, at an Orthodox orphanage, but as she attempts to leave, she is accosted by King Shepherd, who demands the location of the bone. Rocks then fall onto the woman, killing her. The sack then opens, containing an infant girl.

20 years later, Italian-American plumbers Roland and Oliver live in London. They are on the verge of being driven out of business by the mafia-operated Manzo Construction Company led by Filippo Manzo. Oliver falls for London University student Daisy, who is hanging out with some dogs under the Westminster Bridge. After a date, Daisy takes Oliver back to the bridge only to witness two of Scapelli's men sabotaging it by leaving the water pipes open.

Roland and Oliver manage to fix it but are knocked unconscious by Gunter and Wenzel, Shepherd's henchmen, who kidnap Daisy. Roland and Oliver awaken and pursue them through an interdimensional portal that leads them to Dogmension.

Gunter and Wenzel realize they didn't bring Daisy's bone, a fragment which Shepherd is trying to get in order to merge his world with the human world. It is then revealed that Daisy is the long-lost princess of Dogmension. When Shepherd overthrew Daisy's father the king and devolved him into fungus, her mother the queen took her to London. The portal was then closed, but Manzo's men inadvertently reopened the portal when they blasted the cave.

Shepherd sends Gunter and Wenzel to find Daisy and the rock to merge the dimensions and make him dictator of both worlds. However, after Koopa subjects them to one of his experiments to make them more intelligent, Spike and Iggy realize Shepherd's evil intentions and side with Roland and Oliver in the desert.

Daisy is taken to Shepherd Tower, where she meets a Shih Tzu named Domino. Shepherd informs Daisy that she descended from the dogs, believing only Daisy can merge the worlds because she is partially a dog. Eventually, Roland and Oliver rescue Daisy with the help of Todd, a guitarist boy who was devolved into a Chihuahua as punishment.

Eventually, the two worlds merge and Shepherd devolves Manzo into a schnauzer before going after Roland, but Oliver and Daisy manage to remove the fragment from the meteorite and the worlds separate again. In Doghatten, Mario confronts Shepherd and eventually defeats him when he and Oliver fire their devolution guns at Shepherd and blast him with a minibomb.

Shepherd, now transformed into a ferocious, semi-humanoid German shepherd, attempts to kill Roland and Oliver, but they destroy him once and for all by transforming him into an actual German shepherd, which is too intense for him to live through and instead turns him into hundreds of pounds of beef. With Daisy's father restored after Shepherd's defeat, he reclaims control over the kingdom. The citizens celebrate and start "deShepherdizing" which is to destroy anything under Shepherd's influence.

Oliver professes his love for Daisy and wants her to come to Brooklyn with him, but Daisy cannot come until the damage caused by Shepherd is repaired and thus, she wants to spend more time with her father. Heartbroken, Oliver kisses Daisy goodbye as he and Roland return home to London, with Daisy watching them leave. Three weeks later, Roland and Oliver are getting ready for dinner when their story comes on the news and the anchorman says they should be called "Super-Roland & Wonder-Oliver" Daisy then arrives and asks Roland and Oliver to help her and says, "You're never gonna believe this!"

In a post-credits scene, two Japanese business executives propose making a video game based on Gunter and Wenzel, now trapped on Earth, who decide on the title The Super Shepherd Cousins.