Pairing: Draco/Astoria (mentions of Cormac/Astoria, Viktor/Pansy, also hints at various Slytherin ships)
Fic Title: House of Heretics
Link: Riiight here
Rating/Warning(s): R for language; mentions of infidelity and crime
Why This Must Be Read: I'm not a big Draco or Slytherin fan, but even so this story is fairly brilliant. Draco is a consultant to the Ministry and the Aurors (Harry), and together they must investigate the disappearance of Cormac McLaggen. Slumber weaves the mystery together wonderfully, showing potential suspects all the way to the whodunnit reveal and surprise at the end. Besides that, she also deals with a number of things in the magical word so cleverly and logically. The flow and the overall story makes it impossible to put down - and you won't want to until you've finished it.