Law & Order: Special Victims Unit 4x15

The brutal rape, and subsequent death, of a female motorist turns out to be an undercover FBI informant acting as a cyber vigilante for catching online pedophiles to capture the predator trafficking internet porn. The detectives find the victim's husband murdered and follow the trail of evidence for the latest victim she had been tracking, which ​turns into an international case of teenage prostitution, with ties to the Czech Republic.