Hunger (2009)

Five strangers face the unthinkable when they wake up and find themselves trapped. With no idea how they got there they frantically try to figure out how to escape. The disoriented group quickly realise the truth about their situation when they discover another room containing enough water to survive for 30 days… and a razor sharp surgical knife. The intention becomes quite clear. Whoever put them in this place wants to see just how long it will take before the hunger makes them commit unspeakable acts and cross a very deadly line.