ABC | 8:00 pm
The two-hour finale to Season 18 opens as Grey Sloan Memorial is hit with a blood shortage, so the staff sets up a voluntary donation center. Meanwhile, Nick (Scott Speedman) asks Meredith (Ellen Pompeo) to assist him with a patient, and Winston (Anthony Hill) wrestles with the relationship he has with his brother. Owen's (Kevin McKidd) actions to help his fellow veterans come to light. Chandra Wilson and James Pickens Jr. also star. This series, the longest-running primetime medical drama in TV history, will be back for Season 19.