One Track Mind follows Sophia the squirrel as she embarks on a train journey after the death of her friend Flora. Departing from the gloomy, rundown city, reminiscent of her state of mind, she sets out to revisit the beach where she once spent a special day with Flora.

Overcome with grief, Sophia is sombre and unapproachable. With the help of a new friend Robin that she meets along the way and inspiring views of natural scenery, Sophia is brought out of her shell. She begins to process her grief, realising that she is entitled to feel happiness and excitement for life again, while keeping Flora in her heart. Sophia arrives at her destination, discovering that she doesn’t need to return to the dull, depressing city she felt stuck in and will stay in the place that brings her joy and a sense of hope.