Jaimie Alexander returns to "Agents of S.H.I.E.L.D." in "Who You Really Are," which finds Sif on earth and without her memory. In this new clip, Sif emerges on a Portuguese beach, searching for a mysterious entity. Check out the clip below.

"Agents of S.H.I.E.L.D." airs Tuesdays at 9 p.m. EST on ABC.