Crystal Donovan lives for games. Especially when the prize money for the MortalDusk tournament is enough to save her family home. So Crystal has to focus on securing her spot on the official tournament team, but then she gets a text on a mysterious app that she knows she didn't download. In it is a picture of her little sister gagged and bound, telling Crystal that if she agrees to play a game and wins, her sister will live. At first, the games are bizarre but simple - steal a test, bake brownies, make a prank call. But then Crystal realizes that each task is meant to hurt her friends, one at a time. As the games get worse and worse and Crystal loses more of the people she loves, she has to come to terms with her past in order to save her sister.