He encountered Ash and his friends when he returned to shore from his latest dive with what he believed was an emerald necklace. However, his wife confirmed that the find was made of less valuable Green Shards, much to his disappointment. He took it as a sign that he was closer to the sunken wreck of the King Neptune and its rare treasure, so he and group dived down in a submarine to locate it.
After following a Relicanth and getting caught in a rip, they found the ship in a hidden underwater cavern. Adam eagerly explored the wreck and emerged with a treasure chest. The group wanted to take the treasure, but Team Rocket took it instead and destroyed the wreck. After making their getaway, they blocked the entrance to the sea cave. The Relicanth, however, knew a different way out, which allowed Ash and friends to escape and pursue Team Rocket. The Relicanth defeated Team Rocket and Adam had his treasure, though it was different from what he expected. While he thought gold or other precious jewels could be inside, the treasure chest only contained more Green Shards. Although disappointed, Evelyn pointed out they could use them to make jewelry, which made Adam feel a bit better.