The allure of a big-screen biographical drama is simple and almost childlike: in our dream scenario, we're not just watching a movie – we're stepping into a time machine until we're in the presence of Abe Lincoln, Jim Morrison or Mozart. Yet the reason biopics have always fought for respectability – when they so often seem corny – is that few of them truly transport us into the past. The actors rarely look exactly like the people they're playing; the storylines waver between the specific and the generic. Overall, they're just not that authentic.

Once in a while, though, you see a biopic that brings off something miraculous, that recreates a famous person's life with so much care that the immersion we seek is achieved. When you watch Love & Mercy, a drama about Brian Wilson, the angelic yet haunted genius of The Beach Boys, you feel like you're right there in the studio with him as he creates Pet Sounds. And it's a little like sitting next to Beethoven: the film is tender and moving, but also awe-inspiring. Paul Dano, the audacious young actor from There Will Be Blood and Little Miss Sunshine, plays Wilson in the mid-1960s, when he was becoming the greatest creative force in American pop music. The moment we see Dano in the film's daringly off-kilter opening shot, which is just Brian noodling around at the piano and talking to himself, the actor seems to transform into Wilson's very being. The pale, cute moon face, the smile with a hint of a grimace, the disarming spaciness – this isn't just acting, it's channeling of a very high order.

It gets around

Love & Mercy was co-written by Oren Moverman (along with Michael A Lerner), the co-writer of Todd Haynes' Bob Dylan fantasia I'm Not There; and it was directed by Bill Pohlad, who has mostly been a producer (of films like 12 Years a Slave, Into the Wild and Brokeback Mountain). Together, these two have come up with an innovative structure that takes on a haunting resonance. Dano plays Brian at the pivotal moment when he’d climbed to his artistic peak but, through a combination of drug use and commercial pressures began to break down. The film cuts back and forth between this inspiring and tragic saga and scenes set 20 years later, when Brian is played by John Cusack as the wreck he had become. He has placed himself under the constant care of Dr Eugene Landy (Paul Giamatti), a hustler and psychological guru who has succeeded in drawing Brian out of the depths of his depression (he'd spent three years in bed). But Landy has also, in effect, made Brian his meal ticket and prisoner, doping him up on pharmaceutical drugs. This latter-day Brian has been ‘rescued’, but only as a zombie – that is, until the day he goes shopping for a Cadillac and meets Melinda (Elizabeth Banks), who sells cars in the showroom. The two begin to date, because she sees the loving soul beneath Brian’s sadness.

It's jarring, at first, to have Wilson played by two actors. You could argue that it doesn't entirely work, since Dano, who has always been an inspired space cadet, inhabits the role as if born to it, while Cusack, dialing down his usual verbal precocity, simply doesn't look – or feel – like Brian Wilson in quite the same way: when Cusack is on screen, we're out of the time machine, back on more conventional biopic ground. Yet as staged, the story of what happened to Wilson in the '80s is still a marvel of tenderness, discovery and even suspense. Can Melinda pry Brian out of the clutches of Landy, played by Giamatti as a dictator in healer's clothing who will destroy Brian in order to save him? Cusack gives a richly subtle and moving performance, showing us an incomparable artist who's been shattered to pieces. And we want to know: how, exactly, did that happen?

Tuned in

Love & Mercy offers up the answer with delicate fascination and insight. Early on, Dano's Brian tells the other Beach Boys that he wants to stop touring with them and retreat into the recording studio.

It's a surprisingly squashed and narrow space, and as Brian records all the backing tracks, Dano is almost goofy with eagerness, his eyes popping wide, his face split by a crooked grin of joy. His performance shows that Brian was in fact a mere boy when he created his masterpiece. He was only 23, but psychologically he was younger, a kid playing with the ultimate train set.

It's when the Beach Boys return from touring, and get ready to lay down the album's vocal tracks, that conflict sets in. Mike Love, portrayed with likable vigour by Jake Abel, leads the charge against Brian: he doesn't get this dreamy slow music dipped in gorgeous LA twilight. "Even his happy songs are sad!" rails Love. And, of course, he's right: on Pet Sounds, Brian combined happiness with sadness and transformed them into the sublime. But when the album turns out to be a commercial disappointment, superficially vindicating Love's hostility toward it, Brian becomes unhinged. 

The film offers a complex view of what derailed him. It follows Wilson through his piano-in-the-sandbox phase, shows how he pulled himself together to record Good Vibrations and finally, after that song's extraordinary success, it tracks his heartbreaking descent into the insanity of the Smile sessions. Each time the film cuts from Dano to Cusack, the double casting feels more right: it reveals that Brian Wilson, once he'd lost his music, lost himself. He was a different person. Love & Mercy captures how a great American artist created the musical equivalent of grace, then fell from it, yet somehow found himself – and grace – again.

★★★★★

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