 In "ER"'s first season, the core cast consisted of Chief Resident Dr. Mark Greene, pediatric resident Dr. Doug Ross, second-year resident Dr. Susan Lewis, medical student John Carter, head nurse Carol Hathaway, and second-year surgical resident Dr. Peter Benton.The series premiere "24 Hours" sees Dr. Greene considering a move into private practice at the request of his wife, Jen.The episode also sees an attempted suicide from staff nurse Carol Hathaway, who had previously been in a long-term relationship with Doug Ross, and the first day for medical student John Carter.