Allie and Fig wish they were anywhere other than New York, where their mother lies in a hospital bed in a coma. One morning, with Pa acting like a pod person and Aunt Bijou trying out some sort of hug therapy, the twins escape across Central Park to the American Museum of Natural History. Sometimes the dioramas there seem so real that the animals look alive, the trees so green one can almost smell them. In a room they've never been in before, they discover the Lynx scene, its diorama depicting the same European forest where their mother had her accident. The twins start spinning and then, dizzily, they jump. Instead of feeling the cold, hard glass of the diorama, they hear birds, feel sunlight. Suddenly they are in the forest. But when are they there? And how can they get home again? It's scary, but maybe, just maybe, the twins can change the past so that the horrible cave-in never happens, so their mother is fine again, and the bad, sad, mad time never comes at all. The carousel of time keeps spinning, and Allie and Fig must put together the clues and follow their hearts back through the past to Mim and Pa and Aunt Bijou.