When her mother dies, fifteen-year-old Mari is now the only one who can care for her super-smart and exasperating, on-the-spectrum younger brother Conor. Desperate to avoid being split up or put back into the "System," Mari decides to set out in the old family Honda sedan to find their estranged grandmother, the only person who might take them in. Seizing upon Conor's obsession with the upcoming total eclipse of the sun, Mari convinces him to come along on a cross-country trajectory that will include a stop to view this spectacular event. As the two siblings journey from the snarls of LA traffic through the backroads of the Midwest and on toward their final destination in New England, Mari learns a lot about herself, about the world around them...and about their place in it.