A woman, drunk and high on Special K, is taken from a cafe back to her apartment building, where she is raped and beaten in a dark corner of the courtyard. Despite her cries for help, none of the residents who witnessed the attack call the police. Benson (Mariska Hargitay) calls it the bystander effect - sometimes more witnesses means less help.
Upon canvasing the cafe, Carisi (Peter Scanavino) obtains a witness' cell phone video of the three boys that assaulted the victim and uses it to get a positive ID. Unfortunately, they're all residents at a youth center and have likely returned to life on the street.
After catching two of the boys dealing weed and the other soliciting a john, SVU heads to court with a weak slate of witnesses afraid to testify for fear of retaliation. Luckily, a friend of the victim finally summons the courage to testify, helping convict the boys on all charges.