Gretta (Keira Knightley) and her long-time boyfriend Dave (Adam Levine) are college sweethearts and songwriting partners who decamp for New York when he lands a deal with a major label. But the trappings of his new-found fame soon tempt Dave to stray, and a reeling, lovelorn Gretta is left on her own. Her world takes a turn for the better when Dan (Mark Ruffalo), a disgraced record-label exec, stumbles upon her performing on an East Village stage and is immediately captivated by her raw talent....