Olivia's best friend is not imaginary. He’s not a ghost, either. And she's pretty sure he's not a hallucination. He’s just Mason. He is, however, invisible. When Olivia spotted the crying little boy on her front porch at five years old, she had no idea she was the only one who could see him. Twelve years later when new-girl Robin bumps into the both of them and introduces herself to Mason, they are both stunned. Mason couldn't be more pleased that someone else can see him. Olivia, on the other hand, isn't jumping at the chance to welcome Robin into their circle. Jealousy may have something to do with that, but honest fear that Robin's presence will put Mason in danger is soon validated when a strange black car begins showing up everywhere. The race to find out what Robin knows in time to protect Mason from whatever threats are coming becomes Olivia's only focus.

Seventeen-year-old April Parker wakes up in an underground facility, a shock bracelet on her wrist and a five-day countdown on the clock. Dozens of other teens share her inexplicable fate, but their unseen captors never intervene no matter how brutal conditions become. When the ruthless - and unnervingly magnetic - Marcus seizes control, April's trauma-forged instinct is to lay low. But protecting her friends drives her to bargain with the boy she should fear most - a boy whose reality fractures with every tick. Then the countdown ends, and the real terror begins. Powers ignite. Alliances shatter. And predators are born. And with a saboteur among them determined to keep the doors closed forever, escaping what comes next may be the only way to survive it.