THESE days, Kathryn Bigelow ranks as an A-list Hollywood director. After the Oscar triumph of The Hurt Locker, she's back in the headlines with her docudrama Zero Dark Thirty which has come under scrutiny (quite rightly) for its portrayal of torture as a crucial investigative tool in the hunt for Osama bin Laden.
By this point, long-term Bigelow fans might well be wondering what happened to the director they used to know - the one who made films about hillbilly vampires, or FBI agents infiltrating the world of surfing.
To be sure, Bigelow has reinvented herself more than once. There's a world of difference between her first feature, the artsy biker movie The Loveless, and the futuristic blockbuster Strange Days, a sprawling comment on the Rodney King riots that remains her most ambitious artistic and commercial failure.
If there's a persistent ''Bigelow touch'', it might be defined as an oscillation between realism and romance: between sequences that convey frantic, messy physical experience and those that lend the characters - often backlit and moving in slow motion - the quality of myth.
But themes as well as stylistic traits recur across Bigelow's career. Most obviously she makes films about adrenalin junkies: the vampires in Near Dark (who closely resemble actual junkies), the serial killer played by Ron Silver in Blue Steel, the surfers turned bank robbers in Point Break, and the bomb disposal experts in The Hurt Locker, who find themselves at a loss back in the civilian world.
Likewise, the premise of a crime investigation links Zero Dark Thirty with Blue Steel, Point Break, Strange Days and even Bigelow's ill-fated arthouse venture The Weight of Water, all thrillers that trade on the blurring of moral lines.
Maya (Jessica Chastain), the CIA investigator in Zero Dark Thirty, bears an obvious resemblance to Megan (Jamie Lee Curtis), the cop heroine of Blue Steel: two pale, slim women with high cheekbones, vulnerable yet implacable. Both are initially portrayed as rookies bent on becoming full-fledged insiders, as well as women occupying traditionally male roles.
From a different point of view, Maya has some affinity with Lenny (Ralph Fiennes) the anti-hero of Strange Days: a kind of futuristic drug dealer who peddles virtual reality recordings of extreme experiences, from armed robbery to kinky sex.
Lenny is more voyeur than participant, and the same could be said of Maya: a bit like a film director, her job consists of monitoring her targets from a distance, and advising others on when to take action. Yet there's no doubt that both characters are complicit in dark deeds.
While arguments continue over whether Zero Dark Thirty defends or condemns torture, Bigelow's filmography suggests that there's no simple answer. Rather, she accepts the fact of moral ambiguity - and acknowledges that as a filmmaker she shares in the thrill this ambiguity creates.
The idea is summed up in a line from Near Dark, a superbly tense and atmospheric B-movie that might still be her best work: ''The night has its price.''
Zero Dark Thirty is in cinemas from January 31.