what going on?

Charmed 1x17

That '70s Episode

A powerful warlock shows up claiming that he made a pact with the sisters’ mother in which he spared her life in exchange for the girls’ powers. Fleeing him, the three sisters go back in time to the 1970s when their mother was still alive and they try to prevent the pact.

Charmed: S01E17
Apr. 07, 1999

Charmed season 1