This wrenching documentary, profiling the four doctors who still provide third-trimester abortions in the U.S., is remarkable for being so level-headed. Directors Martha Shane and Lana Wilson avoid manipulation, focusing on the doctors’ daily responsibilities and framing abortion as a public-health rather than a moral issue. That’s not to say they ignore the anti-abortion movement; the title refers to George Tiller, the Kansas doctor assassinated in 2009, and there are numerous scenes of protests outside abortion clinics. Yet the doctors’ plainspoken testimony makes the greatest impact; given the constant opposition they face, their quiet resolve comes to seem heroic.