Big things are about the happen at Maple's house. Mama's going to have a baby, which means now there will be four Rittle sisters instead of just three. But when baby Lily is born too early and can't come home from the hospital, Maple knows it's up to her to save her sister. So she and Dawn, armed with a map and some leftover dinner, head off down a river and up a mountain to find the Wise Woman who can grant miracles. Now it's not only Lily's survival that they have to worry about, but also their own. The dangers that Maple and Dawn encounter on their journey makes them realize a thing or two about miracles-and about each other.