Episode 18 of "Angel"
s01e18 Five by Five

Angel and Wesley catch, find and convert a prime witness that is involved in a case against Wolfram & Hart. Knowing that Angel is behind the reappearance of the witness that foiled a major case, W&H are ready for payback. Enter Faith. Seems she's had enough of Sunnydale and is searching for darker pastures. Not five minutes off the Greyhound and the rouge Slayer knocks out a lecherous man and takes his wallet and keys. With some cash and a place to stay, the sky's the limit. We're taken back to Romania, circa 1898, as Angel's past is revealed. We see the transformation of Angelus to Angel as his soul is restored by a gypsy. And we see the pain Angel first endures as he now feels the 140 or so years of killing and is now neither part of the vampire nor the human world. The evil folks at Wolfram & Hart find Faith and commence hiring her to do away with their nemesis, Angel. It's obviously no problem for her. She immediately attempts to shoot our hero in public with a crossbow, but Angel catches it mid-flight. Wesley warns Angel that Faith is not a demon but just a sick girl and there may be a chance to reach her still. Wesley changes his mind when Faith kidnaps and tortures him, nearly to death. Angel and Cordelia follow Faith's path of destruction and locate her new hide-out. Faith and Angel fight but as Faith begins to get stronger physically, declaring herself "evil," she appears to be losing it mentally. As they fight, they both go flying out the window to the alley below. Wesley cuts himself loose, picks up a knife and heads downstairs--ready to do whatever he has to, to save Angel. Faith continues to weaken mentally and as she and Angel brawl in the alley, she collapses into his arms, begging him to kill her. To be continued...