Be careful where you venture.
When Joe and Lucy, lovingly married, enter a derelict house to scavenge, the door locks behind them, trapping the couple in a half destroyed room. Lucy is claustrophobic and needs to get out. When Joe tries to break the lock, unnerving messages written in blood appear on the walls, asking the same thing from both. The price for freedom is steep, and unless they act fast, they will die trapped.