A couple of thrillers for this weekend.

"The Roomate" (pg 13)
A deranged college freshman becomes obsessed with her new roommate.

"Sanctum" (r)

Master diver Frank McGuire has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off in a flash flood, Frank's team - including 17-year-old son Josh and financier Carl Hurley - are forced to radically alter plans.