Scrooge McDuck arrives angry to Donald's House, so Donald hides in his secret Duck Avenger hideout and surveys the outside with a special TV. Scrooge explains to Huey, Dewey and Louie that he wanted Donald to help him moving the furniture of a latin teacher. The furniture is in jail and Scrooge bought it at a poll after the teacher died, having been jailed for teaching Latin at day and thievery at night. After Scrooge and the kids leave, Donald turns out his surveillance TV and goes to Gyro Gearloose's house. There, Gyro gives him a two-color pen whose red point can cut an iron bar and the blue one can re-weld it without trace of the welding. Gyro also gives Donald some sleeping pills.
Donald returns home just in time to see Scrooge and the kids unloading the furniture. Scrooge explains that 20 years ago, the teacher hid more than ten millions in a secret place, became a carpenter in jail and made his own furniture, so there could be some hint of the money, for which the police offers the 20% as a reward. The ducks begin disassembling the furniture in the hopes to find a hint.
A busibody tries to buy the furniture but Scrooge sends him away. Donald notices the man had been following Scrooge's car before, so he uses his Duck Avenger boots to follow him, but an accomplice sends a dog named Nero after Donald, who gives him a sleeping pill. However, he is captured by the rest of the villains, who reveal to be Primus, Secundus, Quintus and Sixtus, the teacher's students who have left prison and want to find the millions. Meanwhile, Scrooge and the kids notice the teacher's pigeons were message carriers, so they take the message but only find the gibberish musrus adroc and a lot of 'Q's. Scrooge dismisses the idea of using the Junior Woodchucks Guidebook to descifer it and goes to Gyro instead. The villains leave Donald tied and follow Scrooge.
Donald unties himself cutting the rope with a rock, and when he arrives home, his nephews tell him what happened, but Donald suspects Scrooge will be kidnapped by the villains before getting to Gyro. It actually happens, and the villains take Scrooge to their hideout, the "Krime School" where the teacher taught them the art of thievery. As Scrooge doesn't have the message, the thieves call to Donald's house and ask for the message in exchange for Scrooge. The kids don't have the message either, so they fabricate a fake one.
That night, Donald and his nephews reunite with the villains, who know the message is a fake because the teacher wrote backwards, so they capture the ducks, taking the 313 with them, and reunite them with Uncle Scrooge in the Krime School. When the four ducks are alone in their cell, Scrooge reveals he had hidden the message under a layer of his hat. Due to the new knowledge about the teacher, Louie gets the musrus adroc as sursum corda which means "hearts up" in latin but Donald is convinced "corda" refers to the rope in the school gym. Donald offers some sweets to Scrooge and the kids, but these are sleeping pills, and while they are sleeping, Donald uses the red pen to cut the window bars and gets his Duck Avenger costume from the 313 trunk.
The Duck Avenger enters the Krime School gym through a door marked with a Q (which explains the 'Q's in the message). He defeats Primus who was guarding, but a shot alerts the others. The Duck Avenger defeats them and then climbs the rope until reaching two heart-shaped rings on the ceiling. The Avenger holds both, which pull a pair of strings that make the boxing ring slide to reveal a hidden trapdoor with the money there. The Avenger returns to the cell where his relatives are still sleeping, leaves the money and keys for the cell there, changes back to Donald and repairs the bars with the blue pen, then he pretends to be asleep when everybody wakes up.
Scrooge sees the money and the kids read a note attached saying "a gift from the Duck Avenger". Then they use the key to open the door and find the defeated villains. As there are ten millions, Scrooge's reward will be two millions, and goes to call the police to get the villains and give him the reward. Scrooge and the kids leave Donald sleeping as he seemingly doesn't know to do anything else, but Donald, who just pretends to be asleep, smiles as he knows what he actually did.