Ash, Iris, and Cilan become lost in Twist Mountain. There they come across an archeologist named Ferris. He is looking for the fossil of the ancient Pokémon Tirtouga. Upon uncovering it, he takes everyone back to his cabin where he reveals that he meet the Pokémon as a child while playing in Twist Mountain and wants to revive it. Meanwhile, Team Rocket's latest plan gets underway as Dr. Zager orders the trio to capture the Cover Fossil so they may open the Gate of Time in Twist Mountain.