Mark’s debut book, Margarash, is the story of a boy named Collin, a monster called Margarash, coins and ultimately friendship.

The Wall Street Journal called Margarash “an engagingly offbeat picture book…that reveals the existence of a vast domain beneath the springs of all couches, everywhere”

From the School Library Journal: “Riddle has crafted two well drawn characters who play off each other in a delightful way.  There are effective page turns throughout, elevating this title from more than your typical ‘confronting the monster in your closet’ story… Readers will be enchanted by the budding friendship between boy and monster.“

Wink Books added Margarash to its site of the “best books that work on paper,” saying that “Margarash puts a clever, modern twist on a classic folktale storyline.”

Margarash was included in School Library Journal Fuse8‘s lists of the Best Picture Books of 2016 and the Oddest Children’s Books of 2016. The author of the lists declares: “So weird.  So wonderfully blissfully weird” and “My kids love this book.  No.  They do.  They LOVE this book.”

Youth Services Book Review gave it a 5++ or Starred Review, describing it as “A perfect book” and that “It reads like a modern-day fairy tale though it has the feeling of age about it: children confronting and outsmarting monsters – and the best part- befriending monsters.”

Publisher’s Weekly said “It’s a story with the feel of a modern-day fairy tale or urban legend, one that suggests that compassion and common ground can go a long way toward making friends out of would-be enemies.”

You can also view reader reviews on Goodreads.