Maeve Merritt must retrieve a powerful djinni and her friend's adoptive father before the djinni's wishes fall into the wrong hands. Now that Maeve has surrendered Mermeros, the djinni she found in a sardine can, she anticipates a dull life in London. However, villains from her past are still hunting Mermeros, who is now with her friend Tommy's adoptive father, Mr. Poindexter. When Mr. Poindexter attempts to use a wish, he and Mermeros vanish, threatening to send Tommy back to the orphanage. Maeve, Tommy, and their friend Alice must use magical flying carpetbags to embark on a perilous quest to find them.

The book is positioned as the second installment in the Wishes and Wellingtons series, appealing to young fantasy readers. Its premise suggests a fast-paced adventure with magical elements, suitable for children aged 8-11. The narrative focuses on a quest undertaken by young protagonists to protect a magical entity and prevent its power from falling into the wrong hands. The description highlights themes of friendship and empowerment for young girls, indicating a positive and adventurous tone.