This storyline is more complex than some of the other Pip and Posy books. The changing dynamic as a new character is introduced elicits deep emotion from a toddler 'reader' as the bond of Pip's and Posy's friendship is threatened by Zac. The menacing seagull's theft quickly grabs the reader's attention and unites the three main characters in a problem-solving mode. Their collaboration produces the nicest sand castle I've ever seen and demonstrates the power of teamwork. Secondary characters throughout the book add another enjoyable dimension. My granddaughter 'read' it over and over again after it was initially read to her. I think this may be my, and her, favorite Pip and Posy story.