Highlander: The Series Season 4 Episode 15 : Promises

In 1755, MacLeod made a promise in order to save the life of a young friend. It comes back to haunt him when Kassim, the Immortal to whom he made the promise, demands that MacLeod assassinate the tyrannical dictator of a small Middle Eastern country. When his refusal gets a good man killed and puts Rachel's life in jeopardy, MacLeod is torn between doing what he believes is right and keeping his promise.