The day Harper finds out she owns a secret magical umbrella is the same day her cat Midnight goes missing. While trying to search for her missing cat, Harper finds out all the cats in the City of Clouds have disappeared. With her friends in tow, both new and old, Harper searches the city. She finds the cats as they are being forced to play in all cat orchestra. Now Harper and her friends must act fast to save them.

The book, which is made light and cheerful with the presence of a magical umbrella and a musically inclined cat orchestra, becomes more and more whimsical with each page. It is able to maintain light-hearted and humorous elements through a finely crafted setting and strong character development. Harper and the Scarlet Umbrella deals heavily with friendship and getting along with people who may be different, either in appearance, hobbies, or choice of pet. Harper comes to face tough decisions and at times feels like she may never win but throughout the story, she learns to persevere and leans on her friends and their special talents as they help every step of the way. Short chapters and a steadily paced mystery makes this a gripping and compelling read.