When an asteroid has an 84.7% chance of colliding with the Earth in four days, eleven-year-old Kemi, who loves scientific facts and probability, assembles a time capsule to capture her family's truth as she tries to come to terms with saying goodbye. Eleven-year-old Kemi Carter loves scientific facts, specifically probability. It's how she understands the world and her place in it. Kemi knows her odds of being born were 1 in 5 .5 trillion, and that the odds of her having the best family ever were even lower. Yet somehow, Kemi lucked out. But everything Kemi thought she knew changes when she sees an asteroid hover in the sky, casting a purple haze over her world. Amplus-68 has an 84. 7% chance of colliding with earth in four days, and with that collision, Kemi’s life as she knows it will end. But over the course of the four days, even facts don’t feel true to Kemi anymore. The new town she moved to that was supposed to be “better for her family” isn’t very welcoming. And Amplus-68 is taking over her life, but others are still going to school and eating at their favorite diner like nothing has changed. Is Kemi the only one who feels like the world is ending? With the days numbered, Kemi decides to put together a time capsule that will capture her family’s truth: how creative her mother is, how inquisitive her little sister can be, and how much Kemi's whole world revolves around her father. But no time capsule can change the truth behind all of it, that Kemi must face the most inevitable and hardest part of life: saying goodbye.