Emerson and Vince are two teens living on the streets. Emerson's mother kicked her out, and Vince has no family at all. Together they are managing to survive, but there's a time limit for that survival.
In fact there's a time limit for everyone. In just over twenty-four hours an asteroid will hit North America, ending life for anyone not fortunate enough to be able to afford a ticket to some safer part of the world.
As Emerson and Vince wander the streets deciding what to do with their remaining hours, they meet Carl. He tells them he has been granting people's final wishes and has decided to pass his remaining money and his car on to the two teens. He challenges them to continue paying it forward.
Time continues to tick down as Emerson and Vince wander the streets offering what they can to desperate people. In between their good deeds, Vince tries to convince Emerson that they should use the remaining gas in the car to take her back home to reunite with her family. Emerson isn't sure she wants to confront the mother who sent her packing or if she would even be welcome if she showed up in these final hours.
Author Lisa Schroeder credits a favorite high school teacher for the idea behind this book - "if you only had 24 hours...." What would you do? Schroeder's characters find satisfaction in helping others as a strange twist of fate works to provide a surprise for them as well.