Caldecott Medalist Brian Selznick presents an epic adventure featuring nearly 300 pages of illustrations. Louise and Merwin are two little sycamore seeds who are forced to leave their Mama tree because of fire. Now released into the unknown, they must navigate a world full of dangers to find a place to put down roots and grow into big trees. Meanwhile, a mysterious voice calls to Louise in her dreams, sending her and her brother on a mission to save life on Earth.