Batman Vol 1 Annual #12 (FN)

The grounds of a crumbling mansion are the scene of the Batman's hunt for two foes-one a ruthless killer, the other, something that may not even be human.

Bruce Wayne is invited to a murder mystery weekend at the possibly haunted Slade Estate in upstate New York in "Slade's Demon".

Then, in "The Back-Up", Jason Todd discovers his friends at school are changing their grades on a computer.