Heracles, to prepare himself for this perilous task made his way to Eleusis, to be an initiate in the Eleusinian Mysteries. This he hoped would cleanse him from the deaths of the centaurs, of which he was responsible, also he might learn how to return from the kingdom of the dead.
From Eleusis Heracles traveled to Taenarum in the Peloponnese, and there found the entrance to the underworld. Heracles asked Athena and Hermes to help him, which they did, Hermes led the uncertain hero down into the dim light of the underworld. Close by the gates of Hades there were two living men chained to the rock, as the hero drew closer he recognized them, Pirithous, king of the Lapiths, and Theseus, the king and hero of Athens. They were being punished by Hades for their attempt to take Persephone back to the face of the earth. Heracles set Theseus free, tearing the chains from the rock, but as he attempted to free Pirithous, the rocks shook as if an earthquake had begun, but it was the wrath of Hades, Heracles moved away leaving Pirithous to his fate. Then the hero came face to face with the Lord of the Underworld. Heracles asked Hades if he could take Cerberus back with him to the land of the living. Hades gave his permission, as long as no weapon was used against the huge creature. (in some versions Heracles shot an arrow into the shoulder of Hades).
To capture the monstrous dog, Heracles gripped Cerberus by the throat and wrestled him with his bare hands, overpowering the ferocious beast, then swinging it across his shoulders carried his prize up to the land of the living and back to the court of the king. As Heracles cast the monster at the feet of Eurystheus. The terrified king trembling with fear, asked Heracles to take the monstrous beast back to the underworld, and if he did he would free the hero of his labors.