Herakles and Kerberos (The Legend of Herakles Book 13)

For his twelfth and final labor, Hera set Herakles the seemingly impossible task of bringing back Kerberos, the triple headed guardian of the door to the underworld. But the snarling monster wasn't Herakles only problem. Hades was not happy about a mortal man violating his domain, and he made his displeasure known.