Abstract: A multistage plunger lift system includes an upper production tubing segment positioned in a wellbore uphole of a lower production tubing segment, with the upper segment having a greater diameter than the lower segment. A lower travelling plunger and an upper traveling plunger are sized and configured to fit and travel within the lower segment and the upper segment, respectively. A plunger lift tool is positioned in the upper segment between the upper plunger and the lower plunger, and includes within its main body a fluid passageway with a one-way valve. A plunger receptacle sleeve at the bottom end of the lift tool receives the lower plunger and includes one or more vents configured to allow fluids to flow around the lower plunger when the lower plunger is received within the plunger receptacle sleeve.