It's a Bad, Bad, Bad, Bad World (Part 1)

Under the guise of sending Chris back to the future, Gideon creates a portal that puts Chris and Leo in a mirrored world where evil prevails. Phoebe and Paige travel to the parallel universe to rescue Chris and Leo, only to find themselves in a battle with their evil counterparts. Unable to vanquish one another, both sets of sisters realize that Wyatt is unprotected and in danger from Gideon.