Staff nurse Mark Grace joined the Casualty team before the beginning of series 12. He started a relationship with Dr. George Woodman. During an operation by an old doctor who was slow and doddery, Mark got impatient and took over to do the operation himself. He then revealed to George that he had trained to be a doctor, but he performed an operation when staff thought he was an SHO; it went wrong, the patient died and he was thrown out of medical school.