Now this is an unsub you can appreciate. 

Except, of course, for the poker sodomizing and the forced acid drinking and the stabbing of people in the neck.

On Criminal Minds Season 9 Episode 21, the BAU is called in to investigate when three people are kidnapped in Memphis Tennessee.

Watch Criminal Minds Season 9 Episode 21 Online

Only the unsub wasn't just interested in kidnapping them (no Unsub seems to ever just want ransom): she was interested in getting details about the night when her sister was put into a coma after suffering a heart attack and hypothermia as a result of alcohol poisoning at a frat party.

The narrative of this episode lead us down an interesting path.

In the opening scene, once the two college girls were attacked, we worried that the unsub was perhaps a sexual predator

Then, when we saw the three captives hanging by their wrists in a dark room, while the unsub wore a pig mask, it seemed certain this was a case of pure sadism. This impression seemed to be confirmed after we witnessed the Unsub pull down the pants of one of the male captives and wield a poker.

It was only as the BAU begin digging in earnest that the layers of the sordid onion began to peel and we started to realize that the unsub was herself tormented by her sister's ordeal - and by the cover-up surrounding it all.

You can probably imagine the rage one would feel if a loved one was gang-raped and forced into alcohol poisoning. And then experience the insult to the injury when the ER doctor reported that the sex was consensual.

The narrative was believable because the progression of discovery was perfect. The addition of the irony - the bereft and grieving unsub wearing a pig mask while dealing with people who were out and out pigs themselves - was cruelly apt.

I can't recall an episode where our sympathies swung from one extreme to the other: from worry about the victims to sympathy for the unsub. We've seen variations on that before, but never quite so vividly. 

Mind you, we weren't allowed to feel complete sympathy for her. I mean, the kidnapping of the sister's friend was way over the top. 

This ugly episode was nicely book-ended by the romantic foibles of Morgan, a man who can best Garcia and Reid in track and field (Criminal Minds Season 9 Episode Episode 18), but is out of his league when it comes to figuring out matters of the heart. 

Good thing JJ, a seasoned pro at this stuff, was there to provide the pep talk he needed.

Final notes:

• I have no idea of the full harmful properties of hydrochloric acid, but it seems unbelievable that someone forced to drink the stuff would remain alive. 
• Loved the vintage Garcia: Eyebrows! Angel! I love you! What you need?
• JJ's impression of Morgan was hilarious!
• The next episode of Criminal Minds Season 9 will play on April 30.

Which of the series couples would you like to see the writers tackle next?

Douglas Wolfe was a staff writer for TV Fanatic. He retired in 2016. Follow him on Twitter