Season 2, Episode 22. While Angel tortures Giles for needed information concerning a ritual, Spike strikes an unlikely alliance with Buffy to keep Angel from destroying the world.
Season 2, Episode 21. Kendra returns to help Buffy when Angel plots to revive an ancient demon bent on sweeping everything on Earth into Hell itself.
Season 2, Episode 20. Xander goes undercover on the Sunnydale swim team after members begin turning up dead, after apparently being skinned alive.