Twenty-five lowercase letters go in search of the runaway Little x in the sequel to Alphabet Adventure (2001) by this mother-and-son team. They find him in a castle inhabited by the menacing Master M. “A little x is just a worthless letter back home,” Little x explains to his pals while dancing on a xylophone for the Master’s amusement. “At least here I have a job.” Readers will notice that the other letters employ words that begin with their names all the time (“ ‘This is terrible,’ Little T said”). All ends happily, but the story is nothing more than a feeble excuse for the art. The younger Wood’s digital illustrations are deliciously crisp and bright. The 3-D–style images pop with detail, giving young readers plenty of opportunity to match letters and objects. Still, it may be a stretch to call this a concept book. (Picture book. 5-7)