The British sector of the woman of letters contacts Sam and Dean, the only ones who can help solve a very mysterious case. But what they don't know is that they may need a bit of help from a detective, his companion and a doctor.
Dean wants to do something special for his first Christmas out of Hell, so he gets Bobby and Sam to decorate and celebrate with him. When he makes a mysterious phone call, Sam and Cas try to carry on, but something's up.
This is a superwholock crossover (in case you didn't read the title *shrugs*) and it is Christmas themed. Just fair warning!