The Evil That Men Do (Buffy the Vampire Slayer)

Summary

When a formerly normal, well-adjusted student suddenly shoots his entire family dead and then commits suicide, Buffy and her gang, accustomed to the baleful influence of the Hellmouth which lies beneath the California town of Sunnydale, start looking for the usual suspects - vampires, demons, witches, whatever. The truth, however, turns out to be harder than anything the Hellmouth can throw at them. This time the evil has no supernatural cause. It's the everyday stuff - drugs, pressure, thwarted love. What's a Slayer to do? First off, dig a little deeper...