Lyta Alexander returns to the station with news that one of the senior staff may, unknowingly, be a spy for the Psi Corps. During the course of the investigation, Susan Ivanova reluctantly admits that she is a latent telepath. The spy attempts to assassinate Lyta, before eventually being unmasked: it is commercial telepath Talia Winters. The Psi Corps had secretly planted an alternate personality in her brain, one completely loyal to the Psi Corps, which now takes over her body and powers and seemingly destroys her original personality. She subsequently leaves the station.

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Wikipedia