This scruffy alt.rock musical is already shaping up to be the sleeper hit of summer. Glen Hansard of the Irish pop group The Frames stars as a lovelorn street busker who bares his soul in song, but keeps people at a distance. Into his life comes lonely single mother/Czech immigrant/singer-songwriter Markéta Irglová. The two have an instant chemistry, but are too shy to act on it. In a genre characterized by showy production numbers and over-the-top emotions, this thoroughly modern musical drama makes its mark with a subdued, melancholy mood and a low-key, lo-fi sense of realism.85 minutes R.