S10, E15: While Detectives Briscoe (Jerry Orbach) and Green (Jesse L. Martin) search for the killer of two underaged teenage girls who were drugged, bound and raped, they discover that one victim's older sister (guest star Ellen Pompeo) is also missing, but if found alive, could be the key piece of evidence against their prime suspect (guest star Sam Ball). When the beaten young woman is recovered but is reluctant to testify against her "boyfriend," Assistant D.A. Carmichael (Angie Harmon) contests her story while fellow A.D.A. McCoy (Sam Waterston) tries to keep the state's rapidly dissolving case intact. Steven Hill and S. Epatha Merkerson also star. Mariska Hargitay and Christopher Meloni of NBC's "Law & Order: Special Victims Unit" guest-star as their respective characters, Detectives Benson and Stabler.