Side mission - Widow's Revenge | Act 1 Dungeon Siege III Guide

You will receive the mission from Ludmila (M3,6) in Raven's Rill. In order to complete it, you have to backtrack to Pilgrims' Road and get to the crossroads before Heroes' Crypt (M3,X3). On your way you will meet Florin (M3,1) who will give you The Unlucky Merchant. On the crossroads (M6,X) turn left and after a short fight you should defeat Boris (M6,1). Afterwards return to the city and collect your prize.

Before you can fight with Boris, you will have to defeat his allies.

M3 - Pilgrims' Road and Raven's Rill

M6 - Boris