On the second level of Admiral Yi's campaign you will get a Japanese captive and a guard that wants to kill him. Then you will get a monk. The guard kills the captive. The captive kills the monk. The monk kills neither. The objective here is to cross the river with a boat that needs a driver and can fit one passenger. Always have Yi in the boat then send over the captive first. Come back for the monk and take him over. While you are there send back the captive. Take the guard while you are there and come back for the captive.