The hardworking men of Engine 99 are responding to a report of a fire in a brownstone, but they're barely out of the firehouse when a cab pulls up in front and blocks them. A distraught cabbie is holding a sick baby that he says a woman left in his taxi, so he took it to the firehouse. This guy's never heard of a hospital? The fireguys take the baby and call for help, instead of putting a firehat on it and letting it adorably help with the ladder at the burning brownstone.

At the hospital, Elliot and Olivia listen as the doctor says the 5-month-old baby has candidiasis, better known as "thrush," common enough in newborns that Elliot's worried he's going to get called out every time some baby is colicky. The baby wasn't sexually abused (I mean, thank GOD the show isn't going down that route), but the doctor says the reason the baby is as sick as it is is that it's got HIV, and the parents didn't do a damn thing about it. "If that isn't a crime, I don't know what is," she says. Try to think up an excuse not to do your work now, Elliot!

Elliot talks to the cab driver, a Mr. Marong, who says he didn't notice the baby in the backseat until it started crying after her mother left. Only when Elliot checks the "cab cam" with the TARU tech, there are no pictures of the woman. Marong fesses up that he turned off the camera because he kept the meter off when the woman was in the car, because pocketing a couple extra fares is the only way to pay for gas these days. Topical!

Elliot confers with Olivia, who tells him Munch didn't find any recent reports of missing baby girls or anything, and Marong doesn't have a record. His cellphone rings, so Olivia goes over to tell Marong she's going to have him describe the woman to a sketch artist. I really think the sketch artists should be like the boardwalk artists who draw caricatures and put everyone in dune buggies or skateboarding, you know? Anyway, that was Warner on the phone: they're needed at the morgue. Oh, God, no, please. Don't you dare. I'm tearing up just thinking about this. Don't DO this to me! For god's sake, I cry at the end of Monsters Inc. when Sully has to say goodbye to Boo and then he goes back into the closet and she gets out of bed to open the closet door and it's her regular closet again! You're really going to kill a baby girl on me?

No, thank God. "Did the baby die?" asks Olivia as soon as they arrive. You know, Elliot probably could have asked that question. Warner says the baby's septic, and Dr. Massey's loading her up with antibiotics. Meanwhile, Massey sent over an oral swab with the baby's DNA. "Why? The baby's not going to be in the system," says Olivia, who really ought to know that there could be a mitochondrial match with the mother, who might be in the system, since a lot of HIV babies are born to women with criminal records. "Junkies and hookers," says Elliot, helpful and compassionate as usual. She got a hit: Joanne Suarez, a "frequent guest" of the correctional system. In fact, she's currently at Rikers.