"Sam learns that former Men of Letters, Magnus, once built a magical box and Sam sets out to find it in the hopes it can cure Dean of the Mark of Cain. However, what he’s not prepared for is the deadly alarm system Magnus set up on the box. When Sam opens the box, he puts both his and Dean’s life in danger."
Crowleys mother sends Sam to get some notes that will decode the book of the damned, which contains a cure for Dean. Unfortunately, the book is locked in a basement safe that makes everybody in the house suicidal if anybody tries to open it. After Sam tries to get in, the safe tricks the houses owner into committing suicide, tries to trick Dean into doing the same, but Dean is able to resist. He goes down to the basement just in time to save Sam who is bleeding himself dry in an attempt to open the blood lock on the safe, which of course was another trick of the safes to get him to commit suicide.
In the end they get it open, retrieve the notes, and leave intact. Of course Dean doesn't know what the notes are for. Sam then takes the notes to Crowleys mother to decode the book... and takes her prisoner to boot. Telling her he won't let her go until she fulfills her part of the bargain.
