Perhaps these men, the Rolling Stones, should not be here, at this time in their lives, doing this – doing it so well and so scarily. It is a Friday afternoon, late April, in a rehearsal space the size of a large garage, on the outskirts of Burbank, California. Keith Richards, the band's rhythm guitarist, stands just a few feet in front of white-haired drummer Charlie Watts, who is following intently as Richards plays the intricate and foreboding opening pattern of "Gimme Shelter" with the delicacy of a man edging through hell. When Richards begins the pattern again, Watts joins on drums, just a shadow behind the guitar's beat, and lead singer Mick Jagger moans a high-pitched spooky howl, sounding like the ghost of a future you never want to see arrive yet can't wait for. Then the whole band – Richards, Watts, guitarist Ronnie Wood, bassist Darryl Jones, backup singer Bernard Fowler and keyboardist Chuck Leavell (who is playing with one hand, as his other tries to staunch a steady nosebleed) – bears down on the song with a menacing roar. Jagger paces back and forth in front of the others, in cat-feet movements, making eye contact with nobody, looking at some space beyond the room's walls – that the band sounds capable of battering through – as he sings his mortal plea: "Oh, a storm is threatening/My very life today/If I don't get some shelter/Oh, yeah, I'm gonna fade away." This song is Jagger and Richards' best collaboration in dread – a vision of ruination and a benediction of mercy. In this room, on this afternoon, it also works as a reminder that, in the moments of creating something so frightening and liberating, these men cannot afford to escape their fellowship. In this space, they have to work together and help one another. "The individual components of the band," says producer Don Was, "merge into this one thing that is the Rolling Stones, and when it merges, man, it's really powerful. When you stop hearing the parts and you see the forest from the trees, it's a huge, powerful entity."