Tender Mercies Psychiatric Hospital is one of the darker places in the Sunshine State, so no one is surprised when young college student Elena Santos dies while under its care.
Even though Elena's death appears to result from a severe allergic reaction, the family asks PI Addie Gorsky to investigate. Though still mourning her father's death, Addie takes the case.
But soon the inconsistencies surrounding Elena's death start piling up, with the tight-lipped and paranoid staff blocking Addie's investigation at every turn. After discovering that Elena was not the inexperienced college student described by her family, but a woman with a haunted past, Addie takes drastic action to unlock the secrets of the Tender Mercies.
Soon Addie is plunged into a deadly chess match with an unseen opponent, a grand master of murder always one step ahead.