Told in their alternating voices, twelve-year-old neighbors and former best friends Cora Hamed and Quinn McCauley begin working together to open a wormhole so they can travel through time to prevent the school shooting that resulted in the deaths of Cora's sister and Quinn's brother.

The Greystone kids thought they knew. Chess has always been the protector over his younger siblings, Emma loves math, and Finn does what Finn does best--acting silly and being adored. They've been a happy family, just the three of them and their mom.But everything changes when reports of three kidnapped children reach the Greystone kids, and they're shocked by the startling similarities between themselves and these complete strangers. The other kids...