Possible Clues:

• One stabs Polish prisoner in point of no return
• Decided to cross this to polish one's image, perhaps
• Polish one's image to make one cross
• Cross it to pass the point of no return
• Leave one bank here for another with no return
• Erase symbol denoting point of no return
• Jewel reported by prisoner marks decisive crossing
• Point of no return: 1BC? No, possibly earlier -- are you tuned in?
• Polish religious symbol represents point of no return
• Bridges are burnt once you've crossed this river