Some fans were so horrified by the episode that they had to read the synopsis instead of watching it to the end.

One of the fans commented:
"I was watching the episode on my iPad and when it went to commercial I caught my reflection in the screen. I looked so mortified and I think I ended up just reading the wiki summary."

It is episode 2 of season 7, titled Proof. The episode tells the story of Ben "Cy" Bradstone, brilliantly played by Andy Milder, a mentally disturbed serial killer who kidnapped blonde teenage girls.

He would tie them up and torture them with sulfuric acid, burning various parts of their bodies and eventually killing them.

The victims served as substitutes for the girl Lyla, whom the unsub had been in love with since high school. As they grew older, the woman married Ben's brother. After learning that his brother and Lyla were having some marital problems, Ben tried to make a move on the woman, and her rejection became the trigger for him to begin killing.

Eventually, he finds the perfect Lyla replacement, his own niece.

Those who have watched the episode all the way through agree that the worst part comes at the end, when Ben's brother, who has always been kind and accepting of him, watches the tape of his brother torturing his daughter.
"The ending was probably the worst and this is very high on my list of TV show episodes I will be skipping," a fan commented.