Two people, stuck in their respective lives, are suffering from a sort of middle aged slump. The high points of their lives are going to the London Zoo and occasionally their respective literary professions. Neaera H. is a children's book writer who watches her water bug looking for inspiration for her overdue next book. William G. works in a book shop after his marriage dissolves, frustrated that his life has come to this point. Turtle Diary is told in alternating points of view from each of the two main characters. Telling their story in tandem, the reader sees them meet, come up with a plan to liberate some the turtles in the London Zoo (which is surprisingly condoned by the turtle keeper), and then take an epic turtle road trip to spring some turtles from the zoological joint. The plot is quirky, but the characterization is serious and impressive. Both characters share their frustrations with their middle aged lives, both reflect elements of the book industry that the introduction suggests Hoban was drawing from his own experiences. The turtle adventure bring Neaera H. and William G. together on an epic English car camping trip where they carefully split the costs of their potentially illegal London Zoo turtle liberation. A relatively short novel, Turtle Diary is a majestic look at some ordinary people who decide to go on an adventure.