<Tr> <Td> <H3> Main cast (edit) </H3> <Ul> <Li> Troian Bellisario as Spencer Hastings </Li> <Li> Ashley Benson as Hanna Marin </Li> <Li> Tyler Blackburn as Caleb Rivers </Li> <Li> Lucy Hale as Aria Montgomery </Li> <Li> Ian Harding as Ezra Fitz </Li> <Li> Laura Leighton as Ashley Marin </Li> <Li> Shay Mitchell as Emily Fields </Li> <Li> Janel Parrish as Mona Vanderwaal </Li> <Li> Sasha Pieterse as Alison DiLaurentis </Li> </Ul> <H3> Recurring cast (edit) </H3> <Ul> <Li> Keegan Allen as Toby Cavanaugh </Li> <Li> Andrea Parker as Jessica DiLaurentis </Li> <Li> Lesley Fera as Veronica Hastings </Li> <Li> Lindsey Shaw as Paige McCullers </Li> <Li> Sean Faris as Detective Gabriel Holbrook </Li> <Li> Ryan Guzman as Jake </Li> <Li> Cody Allen Christian as Mike Montgomery </Li> <Li> Luke Kleintank as Travis Hobbs </Li> <Li> Aeriél Miranda as Shana Fring </Li> <Li> Nia Peeples as Pam Fields </Li> <Li> Nolan North as Peter Hastings </Li> </Ul> </Td> <Td> <H3> Guest cast (edit) </H3> <Ul> <Li> Larisa Oleynik as Maggie Cutler </Li> <Li> Roma Maffia as Lieutenant Linda Tanner </Li> <Li> Torrey DeVitto as Melissa Hastings </Li> <Li> Tammin Sursok as Jenna Marshall </Li> <Li> Eric Steinberg as Wayne Fields </Li> <Li> Vanessa Ray as CeCe Drake </Li> <Li> John O'Brien as Arthur Hackett </Li> <Li> Meg Foster as Carla Grunwald </Li> <Li> Bryce Johnson as Darren Wilden </Li> <Li> Roark Critchlow as Tom Marin </Li> <Li> Wyatt Nash as Nigel Wright </Li> <Li> Nick Tate as Dr. Louis Palmer </Li> <Li> Wes Ramsey as Jesse Lindall </Li> <Li> Nathaniel Buzolic as Dean Stavros </Li> <Li> Jed Rees as Hector Lime </Li> <Li> Joseph Zinsman as Robert Vargas </Li> </Ul> </Td> <Td> <Ul> <Li> Julian Morris as Wren Kingston </Li> <Li> Jim Titus as Barry Maple </Li> <Li> Ryan Merriman as Ian Thomas </Li> <Li> Brant Daugherty as Noel Kahn </Li> <Li> Drew Van Acker as Jason DiLaurentis </Li> <Li> Steve Talley as Zack </Li> <Li> Brandon W. Jones as Andrew Campbell </Li> <Li> Rumer Willis as Zoe </Li> <Li> Nicole Gale Anderson as Miranda Collins </Li> <Li> Brett Dier as Luke Matheson </Li> <Li> Skyler Day as Claire </Li> <Li> Elizabeth Whitson as Leah Matheson </Li> <Li> Mark Schroeder as Brendan McGowen </Li> <Li> Michael Grant as Connor </Li> <Li> Marcia Clark as Sidney Barnes </Li> <Li> Nicole L. Sullivan as Tina </Li> <Li> Rose Abdoo as Dr. Sandy </Li> <Li> Nick Roux as Riley </Li> <Li> Michelle Hurd as Elizabeth Mainway </Li> </Ul> </Td> </Tr> <Ul> <Li> Troian Bellisario as Spencer Hastings </Li> <Li> Ashley Benson as Hanna Marin </Li> <Li> Tyler Blackburn as Caleb Rivers </Li> <Li> Lucy Hale as Aria Montgomery </Li> <Li> Ian Harding as Ezra Fitz </Li> <Li> Laura Leighton as Ashley Marin </Li> <Li> Shay Mitchell as Emily Fields </Li> <Li> Janel Parrish as Mona Vanderwaal </Li> <Li> Sasha Pieterse as Alison DiLaurentis </Li> </Ul> <Li> Troian Bellisario as Spencer Hastings </Li> <Li> Ashley Benson as Hanna Marin </Li>

What episode in season 4 does alison come back