"As if 17-year-old Alexandra Lucas' anxiety disorder isn't enough, mysterious holograms suddenly appear, heralding the end of the world. They bring an ultimatum: heed the warning and step through a portal-like vertex to safety, or stay and be destroyed by a comet that is on a collision course with Earth. The holograms, claiming to be humans from the future, bring the promise of safety. But without the ability to verify their story, Alex is forced to consider what is best for her friends, her family, and herself. To stay or to go. A decision must be made. With the deadline of the holograms' prophecy fast approaching, Alex feels as though she is living on a ticking time bomb, until she discovers it is much, much worse"-- Provided by publisher.