It's Zinnia Gray's twenty-first birthday, which is extra-special because it's the last birthday she'll ever have. When she was young, an industrial accident left Zinnia with a rare condition. Not much is known about her illness, just that no one has lived past twenty-one.

Her best friend Charm is intent on making Zinnia's last birthday special with a full sleeping beauty experience, complete with a tower and a spinning wheel. But when Zinnia pricks her finger, something strange and unexpected happens, and she finds herself falling through worlds, with another sleeping beauty, just as desperate to escape her fate.