Peek a Boo Book. Large format board book. In this colorful peek-a-boo book, small children are invited to peek through the holes on every other page to answer the repeating refrain, ?Who?s in the forest, dark and deep?? The playful, energetic, rhyming text introduces all sorts of creatures that make their home in the forest. Recommended age: 1 to 4 years. illustrated by Jull McDonald.