Estella first comes to Dr. Benton Quest to ask if he and his team will help her find her ornithologist grandfather, who has gone missing in a South American jungle. When Quest casts doubts that the man is still alive, she tempts him with evidence that there is also a new archaeological find waiting for him there.
Quest agrees, and is joined by his usual companions, Race Bannon, Hadji Singh, and his son, Jonny Quest as they travel to the Peruvian rain forest. At some point in their journey, they discover a native boy being attacked by an enormous anaconda. Johnny manages to rescue the boy, who later repays the favor by leading them into a cave to escape swarm of gigantic condors. Along the way, they discover what is believed to be the corpse of the missing ornithologist. However, Estella shows no emotion upon this discovery and immediately suggests that they keep going.Further into the tunnel, the group discovers a few more condors feasting on human remains. While everybody else observes, Estella attempts to steal a precious artifact, which then triggers the doorway to the lost city of gold. While the others take a moment to study the natives from afar, Estella once again moves to pilfer a jewel attached to a golden statue. The four are then imprisoned by the natives. When questioned by Quest about her reckless greed, Estella reveals that she never cared for her grandfather, calling him "some idiotic old man who got lost in the jungle". The young boy from before comes to aid them a second time by breaking them out of the cell. As they attempt to sneak past the natives, however, Estella pretends to fall. The young boy moves to help her back out, but when he does, Estella takes him hostage. She then states that she did not come all this way to leave with nothing, and that as long as she has the life of the shaman's son in her hands, she can demand anything. She then further divulges that the ornithologist was not even her grandfather, but upon finding his statuette and the accounts of his explorations, she was able to learn the city's whereabouts.
Jonny goes after Estella and confronts her atop a high stone bridge. When she reaffirms that treasure is the only thing that matters to her, the titular hero tosses her some to let the boy escape. Jonny tackles Estella as she attempts to grab it, and she falls to her death.