I have a problem with the aggressive monochrome colour-grading Whiplash employs. It flattens out image contrast, needlessly distracting attention from the content it paints over, and for about 20 or 30 minutes that was a quite a big quibble. But as the minutes ticked on, that quibble got smaller, and smaller, and smaller, until it was pulverised by an unannounced thrill-ride, and a supporting actor unleashed. J.K. Simmons creates the most outstanding monster as jazz-tutoring orchestra conductor Terence Fletcher. The character’s psychological barbarism shocks and thrills because of Simmons’ poise, his bottomless voice, his aura of hurricane-like inevitability. You never know what he’s going to throw next, be it at the body or the mind. Together with an edit that never lets up, this completely dangerous adversary realises a brutal script about how far a mentor should push his students to achieve greatness. For the plot’s uses, that mentor could be teaching swimming, painting, yodelling, on the face of it anything. So the chosen drumming could be no more than a story-device. Yet not only do the drums generate a propulsive rhythm of their own, they also make for an original, highly cinematic visual, and it’s a credit to director Damien Chazelle for recognising their potential as a linchpin. Chazelle’s complex thematic conclusion matters less to me than the drama of which conclusion he’ll reach. That is to say, an undeniable, emotionally ferocious knockout.