The West Wing alum makes his debut on the medical drama as military doctor Ethan Willis, whose first mission is saving a shark attack victim.
While this isn't Lowe's first time playing a doctor (he had an unforgettable turn as Liberace's plastic surgeon in Behind the Candelabra), the intensity of his new role called for some intensive training.
"There was a class," Lowe said, sporting a crew cut for the part. "They had four or five different trauma cases set up and we would all rotate through them. There were sutures -- that would be one. Another would be how to incubate someone, or how to put in a chest line."