Ostensibly the plot is that of a book being written by Adolphus "Jim" Spriggs. Grytpype-Thynne blackmails Neddie with a 'compromising set of X-ray photographs'. Neddie decides to pawn himself at Henry Crun's pawnshop to pay for the photograph; however, he cannot leave the pawnshop safe until redeemed.
Neddie uses the ten pounds to redeem himself, but then has nothing to pay off his blackmailers. He discovers that Major Bloodnok has the photographs in a safe. Bloodnok does not have the combination. At this point, the characters begin to alter the book with a typewriter, and everything they write comes true. Neddie forces Bloodnok to work by describing him working. Bloodnok retaliates by doing the same. Bluebottle is written in by the author to help them. He has some "silent explosive".
Neddie and Bloodnok are surprised at gunpoint by Moriarty and Grytpype-Thynne, who had played a recording of an explosion "written in without the author's knowledge". Neddie disarms Moriarty by writing in an empty gun, but Grytpype-Thynne writes in an escape down the Amazon with the photographs. Jim Spriggs, the author, appears and demands that they stop interfering with his book. Bloodnok sends him away by writing "...the author turned and left the room!"
Bluebottle, playing with the typewriter, imagines an attack by "Black Claw and his Chinese pirates", ruining their pursuit of the villains. Reaching the banks of the river, they encounter Henry Crun, who tells them "Someone gave Min a typewriter and here I am!" Appealing to the author, they get a happy ending written for them as Neddie marries his fiancée Gladys Minkwater, but Bluebottle writes that Gladys deserts Neddie for him.