Killing with Kindness (1)

A group of patients who are all on the same ward at a local hospital die within minutes of each other. When the cause of death is found to be an overdose of drugs, and each of the victims has the tattoo 'let me go' stencilled onto their back, Creegan and Taylor investigate the hospital cleaner, Carl Burgess, who is found in possession of items belonging to a senior doctor. Creegan is left unconscious after being attacked at home, but who is responsible?