What a wizard enterprise this is, 500 pages of emails and text messages between Russell T Davies, resuscitator, executive producer and head writer of Doctor Who, and his confidant Benjamin Cook, from February 14 2007 19:48 GMT to March 26 2008 18:25. A few details have been deleted, such as the name of the actor scheduled to play the Doctor's companion had not Catherine Tate extended her guest role into 13 episodes, but otherwise, it's unabridged and, moreover, footnoted.

The declared purpose of the project is to attend upon Davies as he negotiates with his BBC Wales colleagues, writes more than his share of the scripts for the fourth year of New Who, from last Christmas's panto/disaster movie to the series finale, and rewrites almost everybody else's. And to provoke from him masterclasses, rants, confessions, reminiscences, doubts, worries, crushes, lusts and the story of the loss of his third-best pair of trousers off a hanger as he glumly negotiates Soho on the morning after the big launch. (On his way to meet his crown prince, Steven Moffat, since anointed his successor: they share a latte and a moment - one day all this will be yours, if you're crazy enough to desire it.)

Fifteen chapters of that should be far too much even for us fundamentalist Doc-venerators, what with Davies at maximum levels of bumptiousness and woe throughout, candid about his selfishness in the service of a show. ("You. Would. Make. A. Good. Dalek," quotes Cook in a wicked interjection.)

But it isn't far too much. It's the Doctor Who Annual for adults, and it's not nearly enough, should have been 1001 pages, because Davies doesn't need to be writing fiction, shaping stuff retrieved from the flux of his Great Maybe, to be a storyteller. He's the Scheherazade of Cardiff Bay. He's making this up as he goes along. He can't stop the narrative. He keeps Cook up all night at the far end of the broadband connection not just with the latest drafts ("a simple panel of the black floor slides open, and the Tardis drops through, like a stone, gone -!"), but his ability to transform anything into a scene - a vile corporate press party, a sudden necessity to write round a real tragedy in his Crummles-like rep company - then pace those scenes into a tale. Oooh, the way he tantalises Cook through the small hours with reveals of the umpteenth defeat of the Daleks and then, five crucial pages from the end and an hour before dawn, breaks into a snappy exchange about nipping out to Tesco when it opens for a pack of the ciggies on which, alas, he's dependent. Cook: "STAY! WHERE! YOU! ARE!" (Long pause.) Davies: "I didn't fall into the Bay. Mmm, croissant. Still warm. I love a little shop."

Then, when Cook is beyond screaming, and the sun is up, Davies presses send. Only Davies hasn't got the happy not-quite-ending right yet, even though he's far beyond his delivery date; deadlines don't make a whooshing noise as they pass Davies by, but the steady vworp-vworp of the Tardis landing, and taking off, and landing again. Those unsatisfactory aspects of his scripts that melt down the internet after screenings are all attributable to his dedication to the dilatory - procrastination is the thief of Time Lords; plus, during his work on the finale, simultaneous chicken pox and bronchitis. Yet even as he lectures Cook on the undramatic craft of creativity, the practicalities of getting the sardines on stage and off again on the right plate and through the only exit that'll advance the plot, he's a total romantic about writing. It's his love, his drug, his force for change: over the year even invisible, unopinionated Cook emerges as a proper companion who challenges Davies over the last image in the series. And wins. Brilliant. Next chapter.