According to Baloo, he and Ace went to school together, and Ace always excelled at "getting two things - the glory and my goat." When they were adults, Ace is a hot-shot test pilot for the military, and constantly talks down to Baloo as a "lowly" cargo pilot, while regaling several adoring fans with stories of his past daring-do exploits. His trademark is to end any statement with the words, "or my name's not..." snapping his fingers and waiting for his fans to shout, "Ace London!" to which he responds, "You got that right!"
While transporting an experimental jet engine to a military base for testing, Ace warns his men that their mission is top secret, yet he brags openly in the refueling station's bar about the engine and how testing it will make him the fastest man in the world. By this time he has become so overconfident that he makes several sloppy mistakes, and so attached to his "heroic" reputation that he scrambles to shift blame for these mistakes to anyone but himself.
His first mistake is carelessly loading a crate being transported by Baloo onto his plane, while an unwitting Baloo loads the top-secret engine onto the Sea Duck. His second mistake is talking openly to his pilots about their mission over the radio, while on their way to the base, ignoring their warnings that someone might be listening in. This alerts Don Karnage, who wants the engine for his Air Pirates.
When the crate is opened on the base to reveal jars of pickles, Ace instantly realizes his mistake, but quickly declares that Baloo must have stolen the engine on purpose. When General Patton orders Baloo arrested, Ace hastily says he'll get the engine back himself.
Ace rushes to intercept Baloo, demanding that Baloo hand over his plane's cargo, without explanation. Baloo laughs this off and buzzes Ace's plane, forcing him to land, infuriating Ace.
Later, after Baloo has opened the crate and discovered the engine, he rushes back to meet Ace and hand it over. Ace, however, is so furious that he ignores Baloo's radio greeting and opens fire on the Sea Duck with his plane's guns, forcing Baloo to evade and hide in a fog bank. When one of Ace's pilots timidly suggests that Ace shouldn't have fired on a civilian, Ace retorts that Baloo ignored Ace's orders and forced Ace and his men to land their planes. When the pilot suggests that this was Ace's fault, Ace hotly retorts: "Ace London at fault? Never! I want that plane found and destroyed!"
To escape both Ace and the Air Pirates, Baloo and Wildcat rig the engine to the hull of the Sea Duck, and go on a ride that ends with them arriving at the base with the engine. At first, General Patton is prepared to arrest Baloo, but then the echo of Baloo and Wildcat's voices in midair reveals that they succeeded in breaking the sound barrier, an achievement that has made them instantly famous.
Ace arrives, his heroic persona all but abandoned, shrieking that he's the one who's supposed to be famous, not Baloo, who stole the engine. Baloo presents his version of events, and, to Ace's chagrin, Ace's own pilots back Baloo up. General Patton is furious with Ace for misplacing top-secret property and shooting at civilians. Thanking Baloo for testing the engine, Patton asks if there is anything the military can do for him. Baloo says that he still has to deliver his cargo of pickles, but the Sea Duck was damaged in the escape. Patton winks and says he knows the perfect man for the job...
Ace is last seen behind the wheel of his fighter plane, which has Baloo's crate of pickles lashed to the back, and even breaks the fourth wall by saying his infamous catchphrase before sobbing. At the end of the episode, Ace has lost everything - his job as a test pilot, military, duty, his heroic reputation, and his place in the history books - and now has been reduced to a "lowly" cargo pilot.