As Cordy (Charisma Carpenter) and the gang continue to press on without him, Angel (David Boreanaz) joins the Host (Andy Hallett) in a mission to stop a misguided physicist named Gene Rainy (Matt Champagne) from destroying the world by stopping time in its tracks. the Host first becomes aware of the impending disaster when Gene sings a song at Caritas and the Host sees no future for him -- or anyone else. It turns out the guy has a girlfriend named Denise (Darby Stanchfield) whom he knows is about to dump him. Aided by a formula slipped to him on the sly by some Lubber demons, he intends to freeze Denise and himself in an eternal embrace when she shows up at his apartment for one final roll in the hay. Unfortunately, the Lubber demons do everything they can to expand the field of temporal paralysis to include the entire world. Despite some intensive detective work and quite a bit of hand-to-hand combat, Angel and the Host fail to prevent this dastardly event from occurring. Eventually, though, they cause time to resume its normal flow and Gene learns an important lesson about the human heart. Originally broadcast February 6, 2001, on the WB network, "Happy Anniversary" marked season two, episode 13 of the supernatural comedy drama.
by Brian J. Dillard synopsis