Audiences were captivated by Glen Hansard and Markéta Irglová when their musical partnership in the 2006 film “Once” led to a triumphant Oscar victory. However, off-camera, where their fictional romance blossomed into real life, an intense two-year global tour puts their destined connection at risk. Shot in black and white, this documentary offers a close-up view of the excitement and challenges brought on by both love and stardom.