While he was busy, Mr. Monkey reached his long arm through the cage bars and took the keys from Mr. Merry's pocket.

When it was dark Mr. Monkey unlocked his cage door. Then he opened the doors of the other cages.

"Come along, my friends, and follow me!" urged Mr. Monkey. The quiet pool where Mr. and Mrs. Hippopotamus lived was some distance from the animal cages, but Mr. Monkey's procession stopped by on their way out of the zoo.