Caravaggio: A Life Sacred and Profane, By Andrew Graham-Dixon

Caravaggio's was a life of chiaroscuro – from the spotlit blackness of his art to the shadows in his heart

Lucky Andrew Graham-Dixon. It has taken him far longer than he expected – more than 10 years, in fact – to write this book. Which means that it is being published just in time to accompany the 400th anniversary celebrations of Caravaggio's death and, an added bonus, the discovery in Italy of remains that scientists have identified as the painter's. Right now, the galleries of Florence are flooded with fans, while anyone who has been in Rome these past few months can't help but have seen – or stood in – the queues at the Quirinale for its Caravaggio show. For its closing weekend, it stayed open all the way from 9am on Saturday to 10pm on Sunday to ensure the Eternal City's midnight art hags could have their sacred fix.

But then, night-time is the right time for looking on Caravaggio. As Graham-Dixon's endpaper reproduction of the tenebrous Beheading of St John the Baptist reminds you, his man was painting it black long before Goya. Darkness was Caravaggio's stock-in-trade, and what illumination there is in his images is focused with the precision of a spotlight on a movie star. His figures seemingly carved from light, he practically invented film noir three-and-a-half centuries before the fact. Nor is Martin Scorsese's habit of using quick camera cuts to enter a scene halfway through a revolution in storytelling technique. As Marty tells Graham-Dixon, he got the idea from looking at Caravaggio's flash-frozen Judith Beheading Holofernes in the Palazzo Barberini.

But Derek Jarman's homo-hysterical biopic aside, the movies have shown a mystifying lack of interest in telling us Caravaggio's own story. Mystifying because, as Graham-Dixon's page-turner of a narrative makes plain, this wasn't just a life sacred and profane, but one of action, intrigue and dirty deeds. You want a screed of swear words for a script? Few pages of Caravaggio go by without our hero telling someone to shove something up their arse. You want a Goodfellas-style scrap in a restaurant? Just film the scene at the Osteria del Moro in which our hero is served artichokes, some cooked in butter, others in oil, and asks the waiter which are which. "Smell them, and you will easily know," comes the reply. At which point Caravaggio smashes a plate and thrusts its now-jagged edge into the cheek of this "fucked-over cuckold" of a maître d'. You want a bad-shave pimp bleeding to death on a tennis court after a knifing from your hero? Just be sure to write one Ranuccio Tomassoni into your screenplay.

Not, Graham-Dixon contends, that the two men had argued over a game of racquets (as earlier biographers thought). Rather, he says, they were duelling over a woman. Fillide Melandroni was a Sienese courtesan in Tomassoni's employ when Caravaggio met her and asked her to model for him (she is likely the girl he posed as the Virgin Mary in Rest on the Flight into Egypt). Subsequently, she took up with the painter on a more permanent basis, and her former boss was a little put out. Incidentally, Caravaggio may not have meant to kill Tomassoni when he stabbed him in the femoral artery. Graham-Dixon thinks it "entirely possible Caravaggio was... attempting to make mincemeat of his testicles".

Though the lineaments of this story – from Caravaggio's brutish strutting through counter-Reformation Rome to his ennobled exile on Malta and Sicily, through to his impoverished, malarial death on the beach at Porto Ercole – are well known, there is much that is new here. Refreshing to have it pointed out, for instance, that Caravaggio was not gay – not just because he swung both ways, but because the concept of fixed sexuality was unknown to seicento Italians.

No less invigorating are Graham-Dixon's readings of the Caravaggio oeuvre. And though some of his iconographic hermeneutics are a little far-flung, there's no gainsaying the depth of research behind them. "It is often said there is a hidden self-portrait reflected in the carafe," writes Graham-Dixon of the Uffizi Bacchus. "I have inspected the painting under high magnification and there is no such self-portrait." I believe him.