The Price Of Passage is a secondary quest in which you will have to deal with guards bent on relieving you of some of your coins.
Following contains quest spoilers.
You’ve been warned
When traveling near Oxenfurt, you will be approached by two Redanian soldiers asking for a "war tax". They can be found near the fish merchant below the bridge to the west of town. You have two options.
This will cost you 50 Crowns. You can find the bastards a few days later, they will be loitering at Oxenfurt’s south gate. They will again ask for more money (you won’t see them again after this encounter. Make your choice.
Pay them again.
You will not get into a fight with them at this point. After that, you may run into them on the outskirts of Oxenfurt; they will be angry at you for getting them in trouble. You can choose to fight them with your fists or kill them with your sword. The quest will then end.
They will call their superior and accuse you of being a spy. The superior will not take the bait and will threaten to send them straight into battle for extorting money. The quest is over and you can be on your way.