Trapper offers this quest as soon as the player arrives in Yanov for the first time. He needs a group of Bloodsuckers eliminated from the swamp east of the Smoothie (Fen) anomaly, near the cement factory. The threat they pose to stalkers in Yanov is becoming a source of concern. It's safer to approach the site from the east: the Bloodsuckers can be lured one-by-one into the relatively large open area just east of the anomaly yet far away enough from the target to avoid dragging more Bloodsuckers into the battle. There are usually four Bloodsuckers to kill regardless of difficulty setting.