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As Wesley (Alexis Denisof) helps Illyria (Amy Acker) acclimate to her new existence in Fred's body, Angel (David Boreanaz) tracks down Lindsey (Christian Kane) in a prison dimension. After the events of "You're Welcome," the former Wolfram & Hart golden boy is locked into a permanent loop of creepy suburban bliss punctuated by daily eviscerations from a fearsome demon. With Spike (James Marsters) and Gunn (J. August Richards) in tow, Angel hopes to free Lindsey from his torture and pump him for information about the senior partners' master plan. Ultimately, though, Lindsey's jailbreak requires a prisoner swap -- bad news for one of Angel's party. Meanwhile, back at headquarters, a powerful presence makes itself known: super-strong Hamilton (Adam Baldwin), Angel's new liaison to the senior partners. Originally broadcast April 14, 2004, on the WB network, "Underneath" marked season five, episode 17 of the supernatural soap opera. Like Knox and Jasmine before him, new character Hamilton is played by a veteran of series creator Joss Whedon's failed sci-fi series Firefly. The latest transplant is actor Adam Baldwin. As of this episode, Mercedes McNab joins the regular cast and Amy Acker's opening credits have been enhanced to include shots of her as Illyria.