Ruth is thirty two years old and doesn't know if she wants to be thirty three. Her meticulously-ordered lonely life as a microbiologist is starved of pleasure and devoid of meaning. She decides to give herself three months to decide whether or not to end her life, and we read her daily diary as she struggles to make sense of her past and grapples with the pain of the present. 'Thaw' explores what makes any of our lives worth living. Can Red, the eccentric Russian artist Ruth commissions to paint her portrait, find a way to warm her frozen heart?