When mysterious visitors arrive in the Kingdom, Princess Alise, Lucas and their friends go undercover on a secret spy adventure to see if they can be trusted. They will need all of their superior detective skills as well as some super cool gadgets to solve the royal mystery and save the Kingdom.
In the middle of the night a strange masked man goes to the kingdom of Trumbeau. There, he makes a huge hole underneath a bridge near the village where everybody is fast asleep and he disappears. The next morning Derek, Odette and Chef Ferdinand are going to the village to have a meeting and Ferdinand are trying to get some new plants but they are sold to a man named Count Antonio. Ferdinand was very angry with him. Another king with his wife, were friends of King William, Odette's late father. The King told everybody and to Odette that her father once saved his life. Odette mentioned that her father often had told her about that. Ferdinand runs to Derek explaining what happened and he sees that the water from the bridge is coming to them and all the water goes out like a tsunami and he yells to everybody to run for their lives. Even Count Antonio saves a boy. The water had destroyed all the houses and the people don't know where to go and Odette and Derek are trying to help by telling the people to give money so they can build new houses and Count Antonio might help. On his way Ferdinand tries to stop him by forcing him to give him all the plants he had bought, but he tells Ferdinand to have them all leaving him happy now. In the afternoon Queen Uberta, Lord Rodgers, Alise, Odette and Derek and all the people reunite together to help and Lucas and his parents were also there and all are giving money.
Next Morning Lucas's parents now working as tulip farmers and delivering flowers. His father told him to go the palace to give Alise some flowers again. Lucas's mother still remembers how Alise took their son back home and she's happy to have a new life. When Lucas arrives at the palace he gives the flowers to Alise and she was happy but he runs away. Lord Rodgers and Alise hoped that Lucas could stay to play with her. In the middle of the night Lord Rodgers seems to exploring a new star and names it after Uberta (his first love). He suddenly notices a light on a tree. At first he did not know who it was but then he finds out that it is Lucas. Lord Rodgers was surprised where Lucas had learned it and he responds that he had learned it by himself. Rodgers tries to convince him to come at the castle to show him more but than Lucas goes away.
Count Antonio arrives at the Palace with a Man named Bruno with his hunting dogs Kookoo and Cocoa and he gives Alise some Chocolate. Uberta sees Count Antonio, and she falls stupidly in love with him which makes Lord Rodgers Jealous. Soon he has to keep an eye on him to see what he's up to. He makes a team with Alise, Lucas, Jean-Bob, Speed and Puffin to see what is going to happen next. As the three go to Lord Rodgers' secret lair where no one is suppose to go he gives them some bow ties and a necklace. So the plan is that he sends the children to the neighboring kingdom to see what is up. At first Alise had to ask for permission to go there and her parents say yes. So they go to the Kingdom with Puffin while Jean-Bob, Lord Rodgers and Speed are keeping an eye on Count Antonio.
Uberta still in love prepares a wedding cake but Count Antonio has other Plans what he really did is stealing all the money from the people. While the children had arrived at the kingdom Alise knows how to enter and Lucas had to disguise himself as a prince and the elder King Sebastian meet the children while Puffin is after a cat named Jasper (the same Cat Number 9 from The Swan Princess Christmas). The King would appreciate it if the children can find his cat.
Niccolo another mean man also other plans. When the children are reunited with Puffin and Jasper they go near the Port and they discover all the money from the people and they are discovered by the men and they are locked in the dungeon. Puffin and Number 9 finally find them and gives them ties to escape. As they escape they gave back Jasper but they are not leaving without the sword that once belonged to King William. As they are going to escape again they go another way. Later at night Lucas sends Puffin high to contact Lord Rodgers. He asks the children if they are perfect and yes they are. Still Lord Rodgers wants to help Uberta see the truth by making a head shape of Queen Uberta. But Uberta discovers the fake. Then Rodgers informs Odette and Derek about where Lucas and Alise are and Derek goes after them while Odette stays in case they return. Now Uberta realizes that Count Antonio had no feelings for her, and she wants to have revenge.
Alise and Lucas are trying to get away but they get caught by Bruno but are free thanks to Jasper and with a submarine they escape to the ship to get all the money and get back to the kingdom. But they are discovered by Count Antonio himself and tries to kill them, but Lucas risks his life by getting hurt on his right foot and Alise is sent alone. When Derek and Queen Uberta, who wants revenge on him, defeat him and Alise helps her Father and grandmother and Lucas is still hurt but fine enough to go back to the castle and Count Antonio gets away and Niccolo was arrested by King Sebastian. Rodgers and Queen Uberta forgive each other and Lucas and Alise are light-communicating each other and Lucas loves to come to the castle tomorrow.
The next morning Lucas goes to the castle with flowers again, his leg seemed to be better. There is a big celebration honoring Lucas for risking his life to bring Alise back and saving the whole Kingdom and he was now called Prince Lucas. The end of the movie shows Count Antonio ending up on the same Island where Lucas had lived once and the Boggs calling out once again: Meat.
- "We Are One" sung by Odette, Derek, Alise and the Cast
- "Home to Me" sung by Odette
- "Born to be Me" sung by Macy Kate
Voice cast Edit
- Jayden Isabel as Alise
- Grant Durazzo as Lucas
- Elle Deets (Laura Bailey) as Odette
- Yuri Lowenthal as Derek
- Jennifer Miller as Queen Uberta
- Joseph Medrano as Lord Rogers
- Kirk Thornton as Count Antonio
- David Lodge as Niccolo/Number 9
- Clayton James as Jean Bob
- Doug Stone as Speed
- Gardner Jaas as Puffin
- Joey Lotsko as King Sebastian of Borromeo
- This is the first film in the franchise to be rated G by the MPAA since The Swan Princess: The Mystery of the Enchanted Treasure; the previous three films in-between were rated PG.
- There is a continuity error when Rogers takes one of the pendants of Alise's spy necklace. In one shot there are two beads, but in the next there are 3 (even though he had just barely removed one of them).
- King Sebastian's guards wear uniforms identical to Uberta's footmen, except in red instead of green.
- Alise slides down the stair banister just like her parents did in the first movie.
- Bridget's only scene is a cameo at the end of the film.
- Uberta proposes to Rogers and he unwittingly accepts, meaning the two are currently engaged to be married.
- Bromley does not appear in this movie.
- The Statue of Scully is seen in the cameo in Royally Undercover while the Scullons and Scully were absent in the movie.