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 and Zeke celebrate the restaurant's tenth anniversary and it ends with an unexpected bang. Meanwhile, Eleanor and Isaiah sneak out for a night of magic, wonder, and danger. Naomi struggles with new developments in her case while Claire makes great strides.

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.