S2, E19: When the father of one of the dead girls explains that he paid Dennis Lee (guest star Kelvin Han Yee) to have her brought to America, this hits home with Olinsky (Elias Koteas). Lee is one of the Chicago's most wanted fugitives and escaped Olinsky once before. Intelligence isn't about to let Lee dupe them again and Olinsky's past files prove valuable in finding Lee's whereabouts. Meanwhile, Sean Roman (Brian Geraghty) has an altercation with a fellow officer which lands him in a bit of trouble. At the same time Platt (Amy Morton) helps prepare Nadia (guest star Stella Maeve) to take her polygraph test after passing the CPD written exam.