Once upon a time, King Eurystheus of Mycenae and Tiryns, commanded a labor to Hercules, the son of Zeus and Alcmene, to kill the Hydra, offspring of Typhon and Echidna, who lived in a swamp, close to the well of Amymone, and ravaged the land of Lernae near Argos.
The beastly Hydra was a gigantic serpent having nine heads, where eight were mortal heads, which if cut, had the power to grow two more heads in its place; and the ninth head, in the center, was an immortal head.
Hercules arrived at the swamp in a chariot, driven by his nephew Iolaos. Seeing the Hydra, Hercules threw flaming spears at it. Hercules jumped and clung at one of the serpentine necks, while the beast coiled itself on one of his legs. With a mighty blow of his club, Hercules pounded off one head, but to his surprise, two more heads grew in its place. The more heads Hercules pounded, twice more heads grew in their places. While he was ferociously pounding the heads, a giant crab came to the rescue of the Hydra, and bit the foot of Hercules. With his heel, Hercules killed the crab.
Unable to find a way to stop the growing heads, Hercules called Iolaos for help. Iolaos, set fire to some pieces of wood and made few blazing torches. Then as Hercules pounded off a head, Iolaos immediately put a flaming torch on the bleeding stump; thereby, the wound got cauterized and regeneration of more heads was prevented. In this manner, all the heads were pulverized, cauterized and their regrowth stopped. Lastly, Hercules pounded off the immortal head, and buried it under a huge boulder, beside the road going from Lernae to Elaios. Thereafter, Hercules cut open the dead hydra and in its venomous bile, dipped the tip of his arrows, so that the arrows become poisonous and unfailingly kill its prey.
But Eurystheus, noting that Hercules had utilized the help of Iolaos, declared the labor as unacceptable.
Excerpt from the book “Once Upon A Time-II: 150 Greek Mythology Stories” by Rajen Jani