Chalk

Maggie survived the end of the world, but it hasn't really ended, has it?

Stuck in an abandoned building with nearly unlimited supplies, a broken radio, and a book of spells, she bides her time and waits for the monsters to leave. But when her daughter reappears, Maggie can't celebrate because something is not quite right. The two women square off with both their lives hanging in the balance, and all that keeps them separate is a razor-thin chalk circle, hastily drawn by Maggie on the floor.