This is the one where Hotch's ex-wife and kid were being targeted, and Hotch finally gets ahold of her (she's in the house with the murderer, who lied and said he was protecting her,) and, in code, he tells his son to run off, then his ex-wife tells him to tell his son about how much they loved each other and you hear a gunshot and the whole team cries - COMMERCIAL! So they get to the house and Hotch runs in and finds his ex is dead, then he shoots the bad guy several times, but he has like, Superman's bulletproof vest on. So they start this epic fight, and finally, Hoych one-ups him, and just starts beating the he'll out of the guys head. And I was like, "**** YEAH KILL HIM!" Then the team comes in and pulls him off because the dude's way dead. He goes and finds his son and he's fine. And then he gors and hold his dead ex-wife. Literally the saddest thing I've seen on tv. Well, fiction-wise, anyway. The acting was top notch.
At least Hotch has full custody now.