Syfy’s Alphas has lined up a slew of guest stars for Season 2, including cult favorite Summer Glau, The Lord of the Rings vet Sean Astin and NCIS‘ Lauren Holly.

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The sci-fi drama revolves around a secret group of normal people with extraordinary mental and physical abilities. Glau (Firefly, Dollhouse), who was previously introduced as the super-intelligent Skylar Adams, will return for three Season 2 episodes.

Astin meanwhile will appear as Roland, an Alpha with a bizarrely absorptive brain that allows him to assume the memories of others and then replay them like a tape recorder. Holly will play a senator with mysterious ties to a member of the clandestine organization.

Also on the docket for Season 2 are C. Thomas Howell (Southland) as an Alpha with super-speed abilities who has revenge on the mind and returning guest stars John Pyper-Ferguson (Caprica) and Kathleen Munroe (SGU Stargate Universe), playing “Perfect Alpha” Stanton Parish and Dr. Rosen’s (David Strathairn) empath daughter Dani, respectively.

Alphas returns Monday, July 23 at 10/9c.