Gifted with wholesome, girl-next-door looks which she convincingly clouds when danger and darkness loom, A.J. Cook has emerged as her generation's Jamie Lee Curtis by headlining a series of post-modern horror films. The Canadian actress began her professional career as a competitive dancer before getting her first big break at age 17, appearing in an episode of the kid-oriented TV scarefest "Goosebumps" and nabbing a role in the TV drama "In His Father's Shoes," both in 1997. Other made-for-TV fare followed before Cook appeared prominently as Mary Libson, one of the doomed sisters of "The