Charmed
The Truth Is Out There ... and It Hurts
S1 E8:
After a warlock from the future comes to the present to destroy the people who will eventually create a vaccine against warlocks, Prue casts a 24 hour truth spell in order to determine if Andy finds out she's a witch, will he still be attracted to her.
Starring
Brad Greenquist, Brian Krause, Michelle Brookhurst