When a young man is found out for desiring his older brother’s beautiful wife, he must go on a journey into the past to discover the cost of possessing a forbidden prize.

The logic of the premise is lost on me. Why must he discover the cost of possessing a forbidden prize before his time?

After his brother finds out he has the hots for his wife, time travel and forbidden prize ownership do not have a clear cause and effect relationship. I think you mean is he was taken back in time by the ghosts of relationship’s past, to observe a distant relative who managed to get his own brother’s wife and the consequence of those actions. Unlike him, Scrooge was taken back to his own past to see where he went wrong, his goal is to learn to be a better person and avoid damnation. Falling for your brother’s wife, while not ideal, is out of ones control as love will happen whether we like it or not.

The logline should focus on what the main character’s goal is that comes about from being caught out by his brother.