Sixteen years ago, a little girl named Olive was abducted during the darkness of a solar eclipse while her older sister Cassie was supposed to be watching her. She was never seen again. When a local girl goes missing just before the next big eclipse, Cassie—who has returned to her home town to care for her ailing grandmother—suspects the disappearance is connected to her sister, and that whoever took Olive is still out there. But she needs to find a way to prove it, and time is running out.