Our heroes are on the path to Celestic Town, but the road runs through a narrow pass that's blocked by three irritable Psyduck. If Ash and his friends take a detour, they'll miss the Celestic Town Contest, but the Psyduck's Psychic-type attacks repel anyone who tries to get through. Ash and his friends do their best to force the Psyduck out of the way, but none of their Pokemon can get in an effective attack. The Psyduck aren't interested in negotiating with Piplup, either! Team Rocket pops in to try and recruit the Psyduck for Team Rocket, but they too are blasted out of the way.
There must be a reason for the Psyduck's behavior, so Ash hatches a hisky ride on Gliscor and flies ahead to scout the path. While Ash is on his mission, Brock sings and dances to distract the Psyduck. Ash and Gliscor crash-land near a pond filled with more Psyduck, nursing their Eggs--that's way the Psyduck in the pass are on guard! Ash returns and reports to the others just before Team Rocket returns in an attempt to steal the Psyduck. Ash and his friends team up with the Psyduck to beat Team Rocket, earning some trust from the Psyduck.
A Psyduck messenger summons the Psyduck in the pass and everyone runs to the pond in time to see the Psyduck Eggs hatch. As Brock dishes up Pokemon food to help earn the Psyduck's trust, he wonders why the Psyduck are in a small pond instead of nearby Lake Psyduck. When our heroes investigate Lake Psyduck, they're attacked by Muk that have taken over the lake! Ash and his friends send the Muk flying into another pond, which just happens to be inhabited by female Muk. The Muk happily pair up and the Psyduck families return to Lake Psyduck, so the road ahead is clear for the trip to Celestic Town!