Ghost in the Mirror is the 25th and final book in the Goosebumps Series 2000 series.
Plot[]
Jason is constantly complaining on the pranks his older sister, Claudia, pulls on him in his outdated bedroom. One day, his parents get him an old, antique mirror and a dresser from a garage sale. He soon discovers a warning and threatening note on the mirror. Convinced it was Claudia, Jason ignores it, but soon begins seeing things in the mirror that are not in the bedroom. His dog also begins barking at it for apparently no reason and finds himself uncomfortably drawn to the mirror. While looking at it, something comes out of the mirror and he falls down on the ground.
The crab-like creature inside the mirror informs him that he has just died of fright and he must come into the mirror, which contains the afterlife. Jason refuses, quickly realizing that it is not an angel or ghost, but a body-snatching monster from another dimension, which the mirror is a gateway to. Jason grabs a hand-mirror and shines it on the monsters. But they multiply into dozens of mirror monsters, who abduct him and take him inside the mirror. Jason watches in shock, as the monsters take his appearance and slowly take over his life. Jason escapes the mirror and turns the tables on his double, by pulling his eyes out. He throws the monster back into the mirror and hurls a lamp at it, smashing it into pieces.
The next day, a worm-like creature emerges from his dresser and asks if he got his warning note.