Sean, an autistic man in residential care, finds his ordered world turned upside down by the sudden death of his mother. In the absence of a father and siblings, first cousins Isabelle and Lucy, two sisters who don't see eye to eye, find themselves guardians of Sean's finances and care. Tensions boil over and it proves to be a responsibility too far for one sister while the other finds her relationship and career at risk as she struggles to meet the challenge of looking after her grieving cousin's welfare.