First, go over to Irina. Face her, then Dovchenko. Jump on the crates to the hook and rope, and swing to the other side of the gap. Dovchenko is following you. First you will battle in the lab, then on the flat car. After the cutscene, you will be in "Doom Town." Knock over the ten mannequins, jump on the Russians' car, kill everyone that comes out, then hop in the car and make your escape.