"He would then set up the poles, string the line between them, and attach the harness. The C-47 would then come in low and slow, trailing a grappling hook. The hook would snag the line, lifting the harnessed operative off the ground and into the air behind the airplane, where he’d be winched on board."
And here's a written description with some photos. The photos include one of a C-47 about to do a pick up: https://www.ww2gp.org/gliderpickup/
It was the second one, The Dark Knight, when Batman captures the mob accountant in Hong Kong and returns him to Gotham. It would be a pretty memorable scene in any other movie, but just about everything got upstaged by Heath Ledger.
Thanks for the links! The technique with gliders was used to rescue the survivors of the "Gremlin Special" crash, in what is now the Indonesian province of Papua, in 1945.
It is also how banner-towing aircraft pick up new banners. As it involves a sudden increase in weight and drag while flying near the stall and near the ground, it has its risks.
"He would then set up the poles, string the line between them, and attach the harness. The C-47 would then come in low and slow, trailing a grappling hook. The hook would snag the line, lifting the harnessed operative off the ground and into the air behind the airplane, where he’d be winched on board."
And here's a written description with some photos. The photos include one of a C-47 about to do a pick up: https://www.ww2gp.org/gliderpickup/