Tree forts, maple trees—and roaring lions? When Yousuf hears ferocious roaring lions and creepy laughing hyenas in his backyard, he calls the best detectives he knows: Ibrahim and Zayn Khan! With the help of their trusty brown sack, they search for clues and bit-by-bit piece together this extraordinary mystery. Join the third-grade detective duo as they solve the thrilling case of the roaring lion!