Huey, Dewey and Louie suspect Launchpad McQuack to be Gizmoduck, which offends Fenton. During a party in honor to Gizmoduck, most attendants dress as him, so the real one cannot prove his identity to show he isn't Launchpad. An accident happens with the fireworks and Gizmoduck takes them away, except for one that hits MacQuack. Seeing him as damaged as Gizmoduck should be by taking the fireworks away, everybody in Duckburg is convinced he is Gizmoduck (save for, of course, those who already know Fenton's secret).
During the following days, MacQuack enjoys the fame of "being" Gizmoduck, until the Beagle Boys capture him. Gizmoduck rescues MacQuack and convinces hum that making people believe he's Gizmoduck may be dangerous. However, as the Beagle Boys didn't see Gizmoduck and MacQuack at the same time, they are convinced he somehow freed himself and donned the Gizmosuit. This has the Duckburgians even more convinced that MacQuack is Gizmoduck.
MacQuack decides to confess in national TV that he isn't Gizmoduck, but when he says the idea is "as my friend Fenton says, Blabberin' blatherskite". As M'Ma Crackshell is watching the declaration on TV, the TV speaker transmits the password to the Gizmosuit which goes where Launchpad is and turns him into Gizmoduck. However, as he is unaccustomed to the Gizmosuit, Launchpad makes some mistakes that end causing a flood, so he must be saved by an unarmored Fenton.
Days later, Huey, Dewey and Louie have noticed that, after Laucnhpad's clumsiness with the suit, he cannot be Gizmoduck. Fenton is happy to know he's suspect number 2, after... Mrs Beakley?