S7, E7: When construction workers pour the sand into a newly made playground and discover the remains of a young boy, Detective Stabler (Christopher Meloni) teams up with CSU tech Millie Vizcarrondo (guest-star Paula Garces) to investigate,which leads them to resurrect a cold case where four boys disappeared 30 years earlier. As the investigation unfolds, new forensic evidence surfaces but no progress can be made solving this case until Anna (guest-star Lisa Emery) surfaces, claiming her stepfather Robert Sawyer (guest-star Richard Bright) was the killer. Mariska Hargitay, Richard Belzer, Diane Neal, Dann Florek, Ice-T, Tamara Tunie and B.D. Wong also star.