Following the poster released last week, Marvel and ABC have released a new clip from this week's Marvel's Agents of S.H.I.E.L.D. entitled "Who You Really Are", airing Tuesday, March 10 at 9 PM ET on ABC. The clip features Thor: The Dark World star Jaimie Alexander as Lady Sif. Coulson and team come to the aid of a confused Lady Sif, who has lost her memory after fighting with a mysterious warrior whose true mission will send shockwaves through S.H.I.E.L.D. Meanwhile, Bobbi and MacK continue to hide their true mission from everyone close to them, on Marvel's Agents of S.H.I.E.L.D..

Marvel's Agents of S.H.I.E.L.D. stars Clark Gregg as Director Phil Coulson, Ming-Na Wen as Agent Melinda May, Brett Dalton as Grant Ward, Chloe Bennet as Agent Skye, Iain De Caestecker as Agent Leo Fitz, Elizabeth Henstridge as Agent Jemma Simmons and Nick Blood as Lance Hunter. Guest starring are Adrianne Palicki as Bobbi Morse, Henry Simmons as Alphonso "Mack" Mackenzie, Jaimie Alexander as Lady Sif, Eddie McClintock as Vin-Tak, Alexandra Manea as nurse, Lidia Porto as head nurse, Danny Lopes as Bruno, Ben Griesse as Tiago, Ruben Rabasa as Mr. Cardozo and Markell Andrew as officer Carvalho. "Who You Really Are" was written by Drew Z. Greenberg and directed by Roxann Dawson.

Unlike her last appearance in the first season of Marvel's Agents of S.H.I.E.L.D., Jaimie Alexander's Sif has no idea who she is as she literally emerges from the sea. What could Sif be up to? Take a look at the clip below, and let us know what you think before "Who You Really Are" airs this week on ABC.