Highlander: The Series (1992)

S4E18 Through a Glass, Darkly

MacLeod's longtime friend, Warren Cochrane, is grappling with a painful secret that he struggles to recall. Understanding that an Immortal who forgets their true nature is destined for death, MacLeod attempts to assist Warren by revisiting their shared past, recounting their fight for Scotland's independence and their quest to restore Bonnie Prince Charlie to the throne. However, it becomes apparent that MacLeod may have done more harm than good by unearthing memories that were perhaps better left undisturbed.