Mr. Darby and Tank bring the Adventure Scouts into the building known as Hummingbird Hideout, where scientists safely study hummingbirds. Ella wants to learn more about where they are, while Noah wants to know how everyone knows them and where Megan is. Mr. Darby begins his tale about the start of the Secret Zoo.

When Frederick Jackson was young, his father frequently traveled and left him alone with his mother. One day, his mother accidentally fell down the stairs and died in Frederick’s arms; the emotional distance between the father and son grew as both fell into their grief. Once, when they were hiking, a farmer asked them to take a monkey he had on his property—the farmer was selling his farm and couldn’t take the langur with him. When Mr. Jackson saw how happy the animal made his son, they brought it home and built a cage in their backyard. More exotic animals came to their house, and their collection grew. Frederick died young, and Mr. Jackson descended into a state where he associated the captive animals with his son, believing he was keeping his son alive. This belief led to the creation of the Secret Zoo.