There are many ways the world could end. There could be a fire. A catastrophic flood. A supereruption that spews lakes of lava. Ellis Kimball has made note of all possible scenarios, and she is prepared for each one. What she doesn’t expect is meeting Hannah Marks in her therapist’s waiting room. Hannah calls their meeting fate. After all, Ellis is scared about the end of the world; Hannah knows when it’s going to happen.

Despite Ellis’s anxiety—about what others think of her, about what she’s doing wrong, about the safety of the ones she loves—the two girls become fast friends. But time is ticking down, and as Ellis tries to help Hannah decipher the details of her doomsday premonition, their search for answers only raises more questions. When does it happen? Who will believe them? How do you prepare for the end of the world when it feels like your life is just getting started?