On the second day of Pokémon Summer Academy all of the students go to a lake to study Template:Type2 Pokémon, As Ash and Angie are walking by the lake they find two boats and use one to explore the far side of the lake, Dawn and Brock follow using the other boat. After Ash and Angie quarrel over what Pokémon to choose they stumble across a Dewgong and a Sealeo, Ash decides on the Dewgong while Angie chooses to draw Sealeo, but they quarrel again when both Sealeo and Dewgong moves the opposite direction causing Ash and Angie to bump into each other, Meanwhile Dawn chooses a Gorebyss and Brock chooses to draw a Chinchou. Ash decides to get up close to the Pokémon to make the research better, they then return to the bank to finish drawing their Pokémon.
As the group is talking a white flash comes from across the lake and Shinx becomes hypnotized and walks off. After a few minutes the group realizes that Shinx is missing and they start looking for it. When the light flashes again and Piplup becomes hypnotized but Dawn stops Piplup from wandering off, Conway then appears and tells a legend about a light that attracts Pokémon. The group decides to go and investigate the light and they find a cave, and in the cave is a Lumineon whom the light off its tail fin hypnotizes Pokémon and draws them in. Jessilinda finds out about the Lumineon and decides to catch it, but is stopped by Conway's Slowking. After Conway defeated Jessilinda, Brock discovers that the Lumineon had been eating some algae.
When the group returned to the class they did a report on Lumineon and said that Lumineon had been eating algae, and although they got a perfect score, Professor Rowan deducted several points because they left the lake without permission.