When the water planet Pisces falls under attack s a result of Aggregor's attempt to collect the second piece of the Map of Infinity, Magister Pyke (who has been kept in the dark about Aggregor's plan to gather the pieces of the map) calls in Ben, Gwen, and Kevin for help in stopping the attacks. Ben and his friends take their plane o Pisces but immediately meet with trouble. A giant animal attacks them and cracks Kevin's space suit and helmet. Gwen forces him to absorb the material from the plane in order to protect him from the deep sea pressure. Then a native fish alien attaches itself to Kevin's head, giving him the ability to breathe underwater. Magister Pyke greets the group, informs them that Aggregor is headed to planet's core, and tells them about a series of tremors that have been occurring on the planet. The four are then attacked by a school of alien fish and mange to escape, Ben changing into AMPhibian in the process. With the Ultimatrix clock ticking, Ben tries to forcefully get into the core of the planet, but the guards attack him until Magister Pyke vouches for him and his friends. The four get access to the core (which happens to be the only part of the aqua planet that is suitable for humans. The group soon runs into Aggregor, who reveals that the second part of the map is the gravitational multiplier that holds the planet together. He takes the piece (doming the planet to slowly drift apart [as it is made entirely of water, save for the core]) and escapes a combined attack by Ben and Kevin. Ben goes after Aggregor, but when his friends try to follow, the guards (who believe them to be the cause of the tremors) start to attack. Ben fails to stop Aggregor and returns to the core. He then changes into Goop and uses Goop's gravitational multiplier to replace the stolen one. Goop is atomized into the water planet, allowing it to reform itself. This act earns Ben, Gwen, and Kevin the trust of the Planet's inhabitants. Their ship intact, but their mission failed, Ben and his friends go home (kevin leaving the fish that saved his life on Pisces, though it is obvious that the fish had taken a liking to him).