In Albany, New York, high school English teacher Gayle Richards finds out that her husband Doug is cheating on her with Claire, one of her students.

One year later, Gayle has moved to Baker Springs, Minnesota, and takes a job as a substitute English teacher at another high school under the assumed name Laura Ellington.

Things become more complicated when news about her past starts to reemerge, forcing Laura to embark on yet another killing spree to protect her identity and her crimes.

But Laura is witnessed entering the house by one trouble-making student, named Ryan Westerberg, who attempts to blackmail her.

After looking up old newspaper records at a library, Josh finally learns of Laura's past and real identity.

When Ben confronts Laura that same evening in her classroom as she is attempting to pack up to flee town, she attacks and stabs him with a glass shard just as Josh walks in.

Momentarily blinded by a police searchlight that's beamed onto her, Laura loses her balance and falls off the roof, landing some distance below on another part of the building.