When a beloved grandfather is found shot dead in his Florida home, detectives fear his missing ex-wife is also in danger; as they uncover a tangled web of romance, infidelity and betrayal, new questions arise about her involvement in the murder.

Numerous patients at a Texas dialysis treatment center have gone into cardiac arrest, resulting in five deaths in one month. Investigators work with the Centers for Disease Control to expose a chilling connection between the unexplained tragedies