After ten years away, Mark Kane and his daughter, Eleanor, return home to New York City, hoping to find a cure for a rare affliction. Meanwhile their neighbor Naomi Cole, an NYPD Homicide Detective, tries to balance investigating a brutal murder at work with raising her son Isaiah, whose newly sober father has suddenly come back into their lives. Claire Logan, a brilliant scientist, receives a devastating call from her estranged father, summoning her home.

With the assistance of his old friend Zeke, Mark chases down a lead that might help him finally discover a cure for Eleanor. Without Mark's approval, Eleanor sneaks off to Isaiah's talent show while Naomi discovers an unsettling pattern to this string of local murders. Claire, newly reunited with her brother, is forced to make an all-important decision about her future.

Upon learning that Naomi is a homicide detective, Mark covers the tracks of his most recent crime. Eleanor discovers that Isaiah is being bullied at school and seeks revenge. Naomi and her partner Ben make a massive discovery in their case, but it comes at a cost. Meanwhile, Claire is on the brink of a major breakthrough in her own right.

Mark moves quickly to clean up a mess, and Zeke gets roped in to help. Claire is hit with a major setback at the lab and Matthew proposes a solution. Meanwhile, Naomi makes a devastating discovery that confirms her worst fears.

As Mark, Naomi and Ellie work together to make sure Isaiah has the best birthday ever, complicated feelings arise. Claire starts to form a bond with Matthew and continues down a path of no return by taking her research to a whole new level.

The mystery of Eleanor's origin story as a vampire is revealed.

Mark goes on a date with Naomi, but Eleanor realizes his motives might not be as sincere as they seem. Naomi and her partner, Ben, close in on their suspect, Claire, who has found a terrifying new way to advance her research.

Desperate for help, Mark turns to his faith for guidance, but Eleanor decides to help him instead, risking her life. Naomi is visited at work by a formidable new Interpol agent and Isaiah gets heartbreaking news.

Mark and Eleanor turn to Claire and Peter for help, but soon realize they may have a plan of their own. Naomi and her new partner, Debra, make strides in their case, and Naomi uncovers a huge secret.