When it's naptime, Dinopotamus always gets the warm spot in the room. He decides to let the children have his favorite spot. But the spot is no longer warm. This is a mystery. Together, Dinopotamus and the children discover that it's always warm where Dinopotamus sleeps. He lies down on the children's favorite spot during story time, making it warm for the children's naptime. This is a science-based mystery about heat.