Impressionist Week, Day 2: Frank Travalena closes his set by mimicing every president from Kennedy to Dubya. Also, Tenacious D (Jack Black and Kyle Gass) promote their new movie and perform "The Pick of Destiny" with the CBS Orchestra.
After a third young teen is found dead, a paw print tattoo on her lower back, Stabler and Beck investigate the tattoo, which leads them to Broder House, a foster home for young girls. They learn that Chantal was one of a number of girls who had ended up working the streets for a man named Victor. Stabler warns Beck that she can't get emotionally involved in every case, but the two work together to bring down Victor, relying on one of his girls to get the evidence that they need.
When an honored Marine veteran is found dead in a hotel, the NCIS team must find out what happened to him. Soon they realize that the Marine didn't commit suicide and that he was a homeless man. After going through his stuff, they find compromising evidence against him, and Gibbs is determined to prove the man's innocence.
While struggling to keep himself and his translator alive after their helicopter crashes in Siberia, Bob remembers the process in which he went through to become a member of the Unit.