Documentary examining the case of Heather Mook, who was caught red-handed feeding amitriptyline pills to her husband John, an anti-depressant that in large quantities causes confusion. Once the police got involved, they discovered Heather had been dosing John for months, not only with amitriptyline but also with rat killer. They then realised that he had been incapacitated each time he was due to discuss financial issues and that Heather was attempting to cover her tracks after stealing more than £40,000 from John's mother