Michael "Mike" Hornsey is a former plastic surgeon and ex-boyfiend of Lisa "Duffy" Duffin.
Mike formerly worked in Phnom Penh, mostly treating sunburned tourists. However, one day, he met Duffy when she appeared on his doorstep with a young girl who had been injured whilst defending her mother from an acid attack.
In 2006, he helped Duffy to set up her clinic in Cambodia. However, when Charlie arrived to help out he had suspicions about Mike. It transpired that he had been struck off the medical register, which left Charlie wondering why. However, when Duffy overheard Charlie calling Sam back in Holby for more information on him, she wasn't impressed. Mike later suffered a stroke in the market, and opened up about his past to Guppy afterwards. Mike had assisted in helping his mother kill herself and was given a life sentence. He was eventually put into an open prison, at which point he fled to Cambodia to start over. He was soon flown to Bangkok to be treated for his stroke.