By any standards, it takes a great deal of both courage and imagination to combine almost any mathematics with a graphic novel, let alone a topic with such a small potential for anything visual. Although the genre is widely known and enjoyed by certain nations and age-groups, it does not lend itself easily to non-fictional subjects requiring more than a minimal amount of text. There was a mildly popular series released in the UK some 25 years ago, which provided readable biographies-with-pictures of assorted scientists – although not in novelised form. Andrew Granville has collected a number of awards for his writings on number theory; Jennifer Granville is an educator, and Robert Lewis the illustrator with a respectable track record as a storyboard artist. The intention is to weave into a classic noir detective story the basics of the interplay between the distributions of both primes and permutations; the book is derived from the script of a semi-staged play that has been presented at a number of academic venues in North America. The artwork and presentation are both well up to the standard of a mainstream graphic novel – cue moody lighting, mean city streets and morgues, and even with a CSI-type narrative episode added instead would be a decent bargain. The mathematical story itself takes a little time to gain momentum, and its meanderings are at least partly justified by the need to create enough space to fit in any treatment of the underlying number theory. The various characters’ names are almost all by way of hommage to trailblazers in modern number theory; thus we have a heroine Emmy Germain, an amalgam of Emmy Noether and Sophie Germain. There are more names and short quotes appearing all over the place, not only in dialogue but also on shop signs, billboards and computer screens, let alone falling out of dropped books. The graphic story takes pride of place in the book, up to page 181. After a brief but engaging explanation of the naming of the many characters, the game is given away – so to speak – by the section on the underlying theory, covering some 23 further pages. Although the ideas within the graphic part would strike chords with – say – a good A-level student and/or someone with a feel for the history of number theory, this later exposition steps things up to postgraduate level. Formal sub-section headings such as Calibration and Divisors, mixed into a tour d’horizon of developments since the topic came back into fashion, lead the reader through a well-structured and detailed summary of the ideas touched on – of necessity briefly – in the first section. That said, the reader may once or twice feel that a few names and threads (Fermat’s Last Theorem, the Riemann Hypothesis) have been thrown in for effect rather than completeness. The final pages trace and explain the many references in the first section that have not emerged in the theory exposition. The amount of detail that has been consistently woven into the drawings is – in its way – remarkable, and full credit must be given for the sheer amount of imagination used in the offered names and visual puns, not least the accompanying music (which features in the plot of the novel). Even the inside front and back pages are well-stocked with mathematical in-jokes. There is a short and somewhat recherché bibliography. Despite all this excellent work, the target audience is frustratingly unclear. A non-mathematician will undoubtedly appreciate the concept and artwork, but very little of the dialogue – and hence will miss all the subtler parts of the story. A student of maths – whether new to number theory or not – will undoubtedly appreciate both the overall story and many cross-references, even if they find the second section heavy going in parts. This is, perhaps, one for the grown-up mathematician who is not too precious about the sanctity of their subject.