4x14 - Hercules: The Legendary Journeys

While Hercules and his double, the Sovereign, were stuck in the Netherworld, Iolaus traveled back in time to protect young Alcmene. But he couldn't prevent Callisto from killing Hercules' mother. Callisto then found her own family and, through a series of instinctive actions, she killed her mother and father. As more events began to go wrong, Hercules sent Iolaus a telepathic message: Get the Chronus Stone from Xena's scepter to travel back in time without Ares' help. Using a makeshift lightning rod, Hercules joined Iolaus in the past and sent Callisto back into the vortex, setting the timeline right.