Introducing the Third Exciting Mystery in the Grandma Gang Series: Donny, Mary Grace and the Ugly Marbles

Author Cathy Pepe has released the third mystery novel in the Grandma Gang children’s book series, Donny, Mary Grace and the Ugly Marbles. The fast-paced tale continues the adventures of Donny, a curious boy with Down syndrome, and Mary Grace, his smart and loving big sister. The siblings live in California with their grandparents, of which Grandma Cathy is part of a mystery-solving group known as the “Grandma Gang.” Donny, Mary Grace and Ugly Marbles can be purchased at or by visiting

In the exciting new book, Donny and Mary Grace find a set of marbles at the senior living center, but some of them are really ugly and just don’t look right. The siblings discover that criminals are using the senior living center as a base of operations. Only Donny, Mary Grace, and the Grandma Gang can crack the case and prevent the criminals from completing their sinister scheme.

Donny, Mary Grace and the Ugly Marbles will have readers of all ages on the edge of their seats as they flip each page,” Pepe said. “I’m so excited to share this story of Donny and Mary Grace using creativity and wit beyond their ages to solve the mystery. The book showcases themes of teamwork, acceptance and critical thinking that everyone can enjoy.”

Donny, Mary Grace and the Ugly Marbles is available in hard cover, paperback and Kindle e-book. The Grandma Gang book series is inspired by Pepe’s late younger brother, who had Down syndrome and was the basis for the character Donny. Ten percent of net proceeds from book sales will benefit Special Olympics, an international organization dedicated to empowering individuals with physical and intellectual disabilities to become physically fit, productive, and respected members of society through sports training and competition.

Kirkus Reviews recently raved that Donny, Mary Grace and the Ugly Marbles keeps readers on their toes and is, “A warm, well-paced follow-up in an inclusive series that will keep readers coming back for more.”

This book follows Pepe’s acclaimed Mary Grace and Donny’s California Adventures (2021) and Donny, Mary Grace and the Dognappers (2022). Mary Grace and Donny’s California Adventures was a hit with readers, receiving a 4.9 of 5 rating on Amazon and a perfect 4 of 4 rating on OnlineBookClub, which also selected the novel as its book of the month for May 2023. Additional books in the series will be forthcoming. To learn more about Grandma Gang Mysteries, including how to purchase books and support Special Olympics, please visit

About Cathy Pepe

Cathy Pepe is a retired lawyer, mother of two and sister to three – including the real-life Donny. Cathy began writing the Grandma Gang series during the COVID-19 pandemic as an avenue to share stories inspired by her brother. She grew up in Southern California and now resides in Lompoc, CA, where the books are based. While the Grandma Gang Mysteries are fiction, many of the characters and incidents were inspired by Donny and the rest of her amazing family.

Prior to writing the Grandma Gang Mysteries, Cathy was an accomplished lawyer at an international law firm and became the first female partner at the practice specializing in labor and employment law. She attended law school after being at home with her two sons for 11 years, funding her tuition by winning two TV game shows.

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