Star Trek: The Next Generation (1987)

S4E18 Identity Crisis

Stardate: 44664.5. When Geordi and a former crewmate revisit a planet linked to a past Away Mission five years ago, they undergo a disturbing transformation into strange creatures. As they grapple with their new forms, they must uncover the cause of this bizarre evolution and find a way to reverse the effects before it's too late. The journey tests their resilience and camaraderie as they confront the challenges of their altered identities.