The episode begins with a view shot of the supposedly-Princeton Plainsboro Teaching Hospital, a faint, annoying sound in the playing in the background. And as seconds go by, we finally realize that the buzzing, strumming, or perhaps ticking noise was intended to initiate suspense. As if the spoilers swimming around the internet hasn't caused that already. Back to the episode: We see random shots of clinic patients and staff in slow motion, and if you have already watched the episode like I have, you'd notice that the only actual faces we're actually seeing are the people who will be taken...
[Shot of squash court, two girls, best friends, playing against each other. After the game, shot of changing room, they are just about to leave.]
Anna (1st girl): I’ll see you tomorrow. Give you another thrashing.
Leah (2nd girl): Yeah, we’ll see about that! (laughs) Need a lift?
Anna: No, I’ll walk home.
Leah: OK. Bye
[Both girls leave at the same time. Leah gets in her car and drives off. Anna is walking in the same direction. Shot of her heart, beating normally. Shot of her walking. Another shot of her heart, now beating erratically. Shot of her vomiting, then collapsing.]