Becoming Colleen is a documentary about one woman's transition from male to female in the conservative coastal community of Coffs Harbour on the NSW mid-north coast. Having lived most of her life as Colin – a husband, father, policeman, film projectionist and self-declared shoe fetishist – Colleen faces the challenge of transitioning her gender identity late in life.

From early childhood, Colleen knew she was a girl in the body of a boy, but after the untimely death of her sympathetic mother she sought acceptance by suppressing a vital part of herself. Colleen went on to marry Heather and became the father of two sons. It was only later in life that she started to open up to her wife.

After losing Heather to a brain tumour, Colleen finds herself living alone in Lime Tree Retirement Village. She takes the first steps to live openly as a transwoman, and finds some unexpected allies: Heather's best friend Denise, who lovingly helps her select her daily outfit, and the delightful Yvette who comes by to do Colleen's makeup. Social worker Rowena Bianchino supports Colleen as her physical reality contradicts her desire for independence and as the time arrives for Colleen's move into full-time care.