S1·E23 The Brain-Killer Affair

Waverly is poisoned, and taken to a hospital where he is subjected to the rays of a brain-altering machine by THRUSH agent Dr, Dabree (Elsa Lanchester) designed to make him ineffective without killing him. While investigating others who have suffered the same fate, Solo finds Cecille Bergstrom (Yvonne Craig) and together they try to unravel the mystery and save Waverly.