While it doesn’t make the top five episodes according to IMDB, “100” is crucial to Hotch’s character, who was the unit chief before the actor portraying him left the show. The episode is told in flashbacks, as each member of the BAU is interviewed about what happened.
It all starts with Haley and Jack in protective custody. Foyet tortures the U.S. Marshal in charge of them and uses the marshal’s phone to trick Haley into going to a new location. Hotch calls Foyet and feeds his ego, trying to protect his family, but Foyet merely taunts him. As Hotch is driving to get to them, Haley calls him on the same phone Foyet was using. They talk, with Foyet listening in, and Haley realizes she’s about to be killed. In a heart breaking scene that could make even a casual watcher cry, Foyet shoots Haley as she’s still on the phone with Hotch.
When he finally arrives at the house, Hotch and Foyet fight until Hotch subdues him and beats him to death. Then, Hotch finds his son safe and hiding in a piece of furniture, which he’d told him to do in code over the phone. In the end, the woman questioning them over the case asks what would have happened if Hotch hadn’t killed Foyet, and Hotch replies that he would have tried to kill Jack. She concludes that he didn’t act unlawfully. It’s an extremely difficult episode to watch, but it shows the love between Criminal Minds’ most iconic version of the BAU, and an event that affects them for seasons to come.