The detectives back-and-forth about this a little bit, with Fin wanting to know how it is she got all Catholic after the abortion, and Chester spouts some stuff having to do with the Mohawks believing everything in balance, and blah blah blah, and eventually Fin says the test results on the unidentified drugs came back: it's stuff for fertility treatments. And records from the couple's fertility center pinpoint the problem: Sarah's husband's boys are slow swimmers. 'So Sarah knew Shane was the father," says Casey.
Huang's turn! He blah blahs about borderline personality disorder, which may explain Sarah's cutting, and says a lot of the "teachers in the news" who seduce their students have that. He says if Sarah is like that, she won't be able to stay from Shane, even with everything going on, and the detectives decide to tail both of them.
Fin and Chester are on Sarah, who, to avoid the media horde in front of her building, sneaks out the basement wearing a wig and sunglasses. Chester recognizes her, though, miraculously ("My grandfather built that wig" is the explanation). She heads into the subway. Meanwhile, Olivia and Elliot watch Shane hop a bus. It appears they're meeting up, but they lose track of Sarah when Fin goes underground, and his radio doesn't work. So you know this is going pear-shaped somehow.
Shane arrives at a hotel, and Elliot and Olivia get all excited at the prospect of catching Shane and Sarah doing it.
After some perfunctory strong-arming of the forgetful hotel clerk, who tells them a woman arrived before the kid got there, the detectives kick a hotel room door down to find a topless Shane and a topless blond woman, who has her back to us. Since we lost contact with Fin, and since we don't see her face, we already know it's not Sarah. Sure enough, she rolls over and says her name's Felice. Olivia gets on the radio to report Shane's with a "pro." I really hope Felice really is a hooker, or she might be quite insulted.
Elliot hauls Shane out of the room while the kid maintains his innocence (at least when it comes to raping his teacher). Elliot calls him a dirtbag. Olivia interviews Felice, who says this was her first time with Shane (who set up the date by emailing her boss).
Fin checks in, a little too late, to report Sarah's gone into her church, and apparently just didn't feel like being recognized.