Sarah, Tommy and Kevin hit the road in search of William's lost treasure and discover his most shocking secret, and Justin returns from the hospital and makes a startling revelation about his enlistment. Meanwhile, Kitty forms an unorthodox alliance with a Senator.

Guest stars include Tom Skerritt as William Walker, Josh Hopkins as Warren Salter, Kerra Lilla Dorsey as Paige Whedon, Maxwell Perry cotton as Cooper Whedon, Jay Huguley as White Peyton, David Burke as Jack Bishop, David Morton as Treat Williams, Keri Lynn Pratt as Amber Trachtenberg, Shawn Michael Patrick as Jordan Lisco, Rob Lowe as Senator Robert McCallister, Michelle Noh as Michelle, Jamie Martz as Dan, Stephen Bishop as Rick, Alex Reznik as the doctor, Michael Dempsey as Ed and Kathleen M. Darcy as the loan officer.

"Mistakes Were Made," Part 2 was written by Marc Guggenheim and Greg Berlanti and directed by Ken Olin.