Once is the inspirational tale of two kindred spirits who find each other on the bustling streets of Dublin. One is a street musician who lacks the confidence to perform his own songs, and thus works part-time helping his father, who runs a small, vacuum cleaner repair business, whilst he dreams of landing a record deal. The other is a young mother trying to find her way in a strange new town. She works as a house cleaner in an upper-class residence and is struggling financially, yearning for a piano she cannot afford. As their lives intertwine, they discover each other's talents and push one another to realise what each had only dreamt about before. Once is the inspiring story of their budding love for one another.