This case study explores Parent and Child Therapy (PACT), an attachment-based intervention for mothers and children experiencing intractable relationship distress originally developed by Heather Chambers (a Child Psychotherapist and Family Therapist working in New Zealand). We describe the use of PACT with a mother–child dyad presenting a history of severe abuse and neglect. The child had been diagnosed with Conduct Disorder and co-morbid Attention Deficit Hyperactivity Disorder. We consider the themes arising in the therapy, the emotional process experienced by the mother and child, the initial outcome and 10-month follow up. The case study indicates that PACT can be learned and used by practitioners outside of the team that conceptualised and developed it. The case highlights the links between externalising difficulties and attachment disorganisation and points to PACT as a promising treatment for the chronic sequelae of early interpersonal childhood trauma. The need for research and possible directions of this research are discussed.