#18 on the countdown is "The Mystery of Christmas Lost!" from Batman #285 by David V. Reed, Romeo Tanghal and Frank Springer.

The villain of this piece is Doctor Tzin Tzin, who had telepathic powers. He escaped from prison and threatened Gotham City's Christmas in some way. Batman presumed some sort of bomb or something along those lines.

First off, though, Tzin Tzin used his powers (manipulated through vapors he released in the grates below Gotham City) into making people think that the Gotham City Christmas Tree was on fire. When Batman showed up to help out, he was attacked by a BEAR on the tree!

Batman then realized that no one else knew that it was Christmas anymore. Tzin Tzin had stolen Christmas from the minds of Gotham City residents!!

After Batman saved the day, there was only one problem - since he had forgotten it was Christmas, Dick Grayson had not bought his girlfriend any present for the holiday! Luckily, Bruce Wayne has a ton of jewelry lying around, so he just gave one to Dick and the day was saved!