Fifteen-year-old Talulah (Tullie) has a passion for the natural world, and sensitivity to how history mistreated her Choctaw people. Only now, suddenly, "history" gets personal. One day-in the middle of a swim lesson-a message appears literally out of nowhere, inviting her to the twenty-fourth century!

Future folk have been recruiting teens from across time, to travel and explore where adults can't. Along with a computer whiz-kid, a free diver from nineteenth century Ceylon, a cabin boy from 1906 arctic explorations, plus some future-time youths, Tullie is tasked with leading her team to an ice-roofed ocean world, many light-years away! Oh, and-especially for this mission to an ocean planet-the crew includes a Hawaiian octopus.

Braving radiation storms, ice tunnels, and lightless watery depths-plus a helpful but unreliable robot-Tullie and her comrades face a ticking countdown. They must find a way to protect this amazing world's ecosystem before it's too late!