How does a lock really work?
Cass sees her sister every day. Nothing strange about that, right? Except Andie’s dead and Cass doesn't believe in ghosts ...
When Cass meets Griff, a mysterious urban explorer who can open any lock, she enters a world of breached boundaries that strangely mirrors her own — only Griff takes it to extremes.
As they explore the secrets of locked buildings, events take a dangerous turn. But can Cass save herself and fight for what is real, if it means letting her sister go?