Orso the Thrid

King Phillip (voiced by Jared Harris) falls ill, and his troll son-in-law Orso (voiced by Sam Rockwell) and his daughter Princess Trista (voiced by Emily Blunt) are next in line to be King and Queen of Cantervale. Orso declines, insisting that a troll as king is a bad idea and that there has to be someone else for the job. With his final few breaths, the king tells Orso that one other heir can become the new King of Cantervale: his nephew, William Casper (voiced by ). After a mournful funeral, Orso sets out on a quest to bring back the new king, along with Doug (voiced by Ron Funches) and Sebastian (voiced Diego Luna). As they're sailing off, Trista runs to the dock and announces to Orso that she is pregnant and he is going to be a father. Shocked, Orso begins to have nightmares about his future children on the journey to find William. Doug tries to comfort him by singing "Cat's in the Cradle," but this only aggravates him more. Doug tries to convince him that his life will not be ruined, but Orso states that he is worried about ruining his child's life.

The trio's journey soon leads them to Barnsley, a town in South Yorkshire, where they discover that William Casper ("Billy", as he prefers to be called) is a scrawny 15-year old underachiever picked on by virtually everyone, from the cool kids down to the retainer wearing Dungeons and Dragons geeks to his abusive teachers and his bullish older Half Brother, Jud. Far removed from the courageous legend his name evokes, Billy stands literally at the bottom of the school food chain. He is constantly showered with insults, used as a punching bag by the Classmates, led by the obnoxious Luc Dewoq (voiced by John Krasinski) and cruelly scorned by Gwendelyon (Latifa Ouaou), the girl he had always loved.

At the school pep rally Orso tells him he's going to be the new king of Cantervale. Billy is only too excited to be on his way to the throne, until Doug and Sebastian inadvertently scare him by talking about responsibilities of being king. Panicked, Billy tries to take control of the RV and ends up crashing it on a remote forest where they meet Billy's retired wizard teacher, Wilbur Filmore (voiced by Simon Pegg). Meanwhile, a revenge-lusted Prince Rupert (voiced by Hugh Laurie) has gone to the Flying Dog Bar, where he encounters a slew of villains, and an assortment of outlaws, black knights, pirates, ents, and witches. Although they initially despise Rupert, he persuades them to join him in a fight for their "happily ending". The villains feel their side of the story has never been told and now is the time to do it.

Charming and the other villains invade the kingdom and pillage for a time before attacking the castle, disrupting friends Dragon, and Doug and Dragon's children. Fiona and Rose (Julie Andrews) try to escape through an underground passage; the ladies are captured, however, when Eve betrays them and leads them into a trap. They learn that she is in love with Rupert, who plans to make her his queen once he claims the throne.

Captain Hook and some of his pirates track Orso and company to Wilbur's cottage, attempting to capture Orso and kill the others. However, Orso and Billy tag-team them effectively and send the villains running, but not before Hook mentions Rupert and the takeover of Cantervale. Concerned for his wife and his future children, Orso urges Billy to return to the safety of Barnsley; Billy, however, has other ideas. He cons Wilbur into coming out of retirement long enough to use his magic and send them all back to Cantervale; the spell works but accidentally causes Sebastian and Doug to switch bodies because they touch each other. They find that Rupert is bent on revenge against Orso for 'stealing' his "happy ending" and plans to kill Orso in a play later that night. Rupert's men arrive shortly, but another clever ruse by Billy tricks the knights into not taking them into custody. They then break into the castle, where play rehearsal and set design are in full swing and where Rupert is becoming not good at rehearsing and is also not good at mock battles, killing two faux Orso in a row. In Rupert's dressing room, Orso menaces Rupert, but Rupert summons his men, who burst in and take the four captive.

Rupert prepares to kill Billy, believing he's the next king. To save Billy's life, Shrek tells Rupert to let Billy go and said he needed a fool to take his place as King of Cantervale. Rupert believes Shrek and decides not to kill him. Billy, who had just been growing to trust Shrek, is crushed that Shrek used him and angrily storms off. Rupert then says to Shrek, "You really do have a way with children, Shrek." which broke his heart. Donkey and Puss are thrown into the tower with Fiona and the other ladies, where Fiona is growing frustrated with the other princesses and their lack of initiative. Queen Lilian soon grows fed up and successfully smashes the stone wall of the prison by head butting the walls. While the women launch a rescue mission for Shrek, who is being held captive elsewhere, Donkey and Puss work to free Gingy, Pinocchio, the wolf and pigs, Dragon, and the Dronkeys. As they prepare to enter the castle and join the ladies, they encounter a still-upset Billy, and Puss and Donkey explain to him that Shrek lied to save him, reminding him that his life was on the line and Shrek saved him at the last minute.

As the kingdom watches, Charming stages a theatrical performance in which he heroically rides to the rescue of Rapunzel in a (fake) tower and sings somewhat badly. To Rupert's profound annoyance, the chained Shrek wins the audience's support by ridiculing his singing and acting. Just as Charming is about to kill Shrek, Fiona and her friends, along with Puss, Donkey, and the Fairy Tale characters, leap onto the stage to confront the villains. It goes awry, however, as the villains largely outnumber the heroes and take them prisoner again. Billy arrives and convinces the villains to stop and turn over a new leaf in the nick of time, proving himself to possess effective leadership skills. He says something that Shrek told him when they were sitting around a fire at Wilbur's Cottage- "Just because some people treat you like a loser, it doesn't mean you are one. The thing that matters most is what you think of yourself. If there's something you really want or someone you really want to be, then the only one standing in your way is you." The villains drop their weapons and release their captives.

Charming, furious at having been thwarted, lunges for him with his sword. Shrek blocks the blow and appears to take it in his own chest, leading Charming to believe he's won, but Charming missed, and the sword is lodged harmlessly under Shrek's arm. Shrek informs Charming that he needs to keep looking for his own happily ever after because he's not giving up his own. As Shrek pushes Charming aside, Dragon slyly knocks over Rapunzel's tower, which lands on Charming, possibly killing him. Charming's crown is sent rolling across the stage by the impact and is caught by Billy. Shrek tells him that the throne is his if he wants it, but it is his decision to make. Billy lifts the crown toward the audience, who cheer for him loudly, then sets it on his own head. While the kingdom celebrates their new monarch, Merlin appears and restores Puss and Donkey to their proper bodies, though their tails were temporarily mismatched.

As Cantervale is left in the capable hands of young Billy, Shrek retires with Fiona to their swamp a few months later, becoming the parents of ogre triplets.