Buffy the Vampire Slayer: No Future for You (Volume 2)
by Joss Whedon, Georges Jeanty
Faith. And Giles. And Amy. And Willow. This was a great set of comics. It collects issues #6-10 in a story arc that has Giles sending Faith to investigate a slayer who is a little insane and being manipulated into killing girls. When it comes to the hard calls, Giles sends who he knows can deal with it--and that's not Buffy this time. Faith knows what it's like to kill and knows what it's like to be manipulated by a man she trusts.
Considering this volume was dark, it'll be interesting to see where the series goes from here.