The Twelfth Labor of Heracles: Cerberus
Capture and bring back Cerberus: “The final labour that Heracles had to complete was to capture Cerberus, the three-headed dog and guardian of the Underworld. Before going to the Underworld, Heracles decided to be initiated in the Eleusinian Mysteries, so that he would be taught how to travel alive from the world of the living to the realm of the dead and vice versa. He then went to Tanaerum, where one of the entrances to the Underworld lay, and was helped there by Athena and Hermes. The goddess Hestia also helped him with negotiating with Charon, the boatman that guided the souls over the river Acheron towards the Underworld.
Once he reached the Underworld, he met Theseus and Pirithous, the two heroes that had been incarcerated in the Underworld by Hades for attempting to steal Persephone. According to one version of the story, snakes coiled around their legs and then turned into stone. A different version has it that the god of the Underworld feigned hospitality and invited them to a feast. However, the chairs on which the heroes were seated magically caused forgetfulness, thus keeping them there. Heracles pulled Theseus from his chair, managing to save him; however, part of his thigh was stuck to it, thus providing an explanation of the supposedly lean thighs of Athenians. When the hero tried to save Pirithous, though, the earth started trembling; it seems that because he desired Persephone for himself, it was so insulting that he was not allowed to leave.
Heracles found Hades and asked him to take Cerberus to the surface. The god agreed on the condition that no weapons should be used to achieve it. Heracles managed to subdue the dog with his hands and brought it on his back to Tiryns. Eurystheus fled in horror into his jar and asked Heracles to take the monster back to the Underworld, releasing him from any other labours.”