Falling Skies is adding two familiar faces for its second season, with Terry O’Quinn and Brandon Jay McLaren both set to guest star.

O’Quinn, best known as John Locke on Lost, will play Arthur Manchester, a former history professor who once mentored the show’s lead, Tom Mason. He is due to appear in the two-part season finale. McLaren, from AMC’s The Killing, joins as Jamil Dexter, an engineer and technology expert who becomes part of the survivors’ camp across a run of episodes.

A TNT drama executive-produced by Steven Spielberg, Falling Skies is set in the aftermath of a devastating alien invasion. Noah Wyle stars as Tom Mason, a history professor turned reluctant leader of the 2nd Massachusetts, a civilian resistance group fighting to survive and push back against the occupiers. The second season is due this summer.