This review (and the episode) does carry a trigger warning for discussion of suicide and self harm.
"The Werther Effect" was the term coined for an uptick in suicides following the 18th century publication Of Johann Wolfgang Goethe's "The Sorrows of Young Werther" wherein the heartsick protagonist commits suicide rather than live separated from the married object of his affection. That's a pretty heavy and awesomely obscure reference to insert into an episode title, but as he has done in every episode he's written since joining the Supernatural writing staff last season, Robert Berens, delivered us an episode as complex, rewarding and dark as the title promised.
The plot of the episode was relatively simple. To decode the Book of the Damned for Sam, Rowena (sigh. I love her) needed a codex which was stolen from the grand coven by the Men of Letters. It was housed in "the Werther Box," which was in an abandoned Men of Letters house in St. Louis. Tinkering with the box released an enchantment that sent nearby victims into hallucinations that made them commit suicide. This was portrayed in incredibly creepy fashion in the 70s-set cold open where a young girl named Susie found the box and woke to find her family dead by their own hands.
The theme of suicide and resilience was explored in very interesting ways throughout the episode, as both Sam and Dean were touched by Werther's spell. On the one hand we have Dean, who was sent into a hallucinatory flashback to his time in Purgatory. The voice of his supposed conscience was provided by the dearly departed vampire Benny (Ty Olson), who tried to push Dean to end his life because it was the only way to protect people. In essence, Benny wanted Dean to give up fighting in order to save the people he loves (that is, Sam and Cas). Dean however refused to break and instead chose, as he has done for many episodes now, to keep going as long as he can. The fact that the Mark of Cain probably won't let him die was also a factor.
Whereas Dean's inner demons (or vampire, as it were) wanted him to give up, Sam's inner-witch prayed on his compulsion to not stop, ever, until he has saved Dean. Aided by what turned out to be a hallucination of Rowena, Sam almost managed to get the Werther box open, but at the cost of his life. Thankfully, Dean steped into the add his own blood to the price demanded of the box, saving them both. The message we get loud and clear is that Sam's determination to save Dean alone (and without Dean's input or consent) is damn near suicidal. The brothers are better together, when they're being honest to each other and if Sam was looking, he might see that Dean is capable of saving himself in some ways. But Sam is too focused on a lot of guilt and fear to do this.
This marks the third extremely satisfying Supernatural in a row, which is doubly impressive considering the stellar quality of season ten so far. As usual, Berens delivered a nuanced episode with twists that actually caught me off guard, subtle characterization and more than enough subtext to keep my little meta-analyzing heart full of joy. I'm extremely excited to see where Sam's story with Rowena (especially ow that she's basically a prisoner!) is going to go, and how this season is going to work out!
Also; the episode gave us this: