Henry Haynes and the Great Escape

When Henry Haynes complains that his new book is boring he falls down into the story and finds himself eyeball-to-eyeball with Brian, a bossy boa constrictor who's in charge of a zoo escape. Brian won't let Henry return home until he's released the animals, including three hungry lions and Gordon - the smelly gorilla who masterminded the escape plan. To make matters worse, it looks as if Gordon's out to get Henry... Can Henry get home alive? And why didn't he just keep his big mouth shut about boring stories?