It's nonfiction. The author researched and presented the events and details in 'In the Garden of Beasts' based on real history, making it a nonfictional work.
It is fiction. 'The Secret Garden' is a well - known fictional story. It contains elements like a hidden garden, magical changes in characters, and a story that is more about imagination and creativity rather than real - life events.
Well, it has elements that are clearly made - up. For example, the way the garden seems to have a magical effect on the children. In real life, gardens don't usually make sickly children suddenly healthy in such a mysterious way. So it's fiction.