Plot summary
When injured people suddenly stop healing and fires begin failing, Xena realizes that Hera has chained Prometheus. Humanity is losing the gifts he gave it. An oracle directs her to the Sword of Hephaestus, the only weapon capable of breaking his chains, and warns that Hera's followers will try to stop her.
Xena survives the cave's soldiers and traps and retrieves the sword. Hercules then demands it from her. Their apparent rivalry conceals the same intention: each knows that the person holding the sword when it strikes the chains will die, and neither wants the other to make that sacrifice.
They agree to travel together, accompanied by Gabrielle and Iolaus. During the fighting Iolaus is wounded. He conceals the injury because nothing can heal him until Prometheus is free, but the climb eventually becomes too much. Gabrielle stays with him while Xena and Hercules continue upward.
The journey allows both pairs to acknowledge their affection. Xena thanks Hercules for helping her change her life, and he admits how much she means to him. She then knocks him unconscious and takes the sword, determined to make the final sacrifice herself.
Hercules follows and joins her against the creatures surrounding Prometheus and the giant eagle sent to devour him. They find a way to send the sword into the chains without either holding it at the fatal moment. Prometheus is freed, restoring fire and healing to the world. Iolaus recovers.
The four part with renewed affection. Gabrielle and Iolaus share a kiss, while Xena and Hercules acknowledge the bond between them before resuming their separate journeys.
Credits
Adapted from Legendary Journeys Wiki contributors, Prometheus (episode). Complete episode narrative, rewritten and condensed for clarity; causal developments and the episode's ending retained. Illustrations, dialogue quotations and non-story metadata omitted.