Saskia and Wendy - Dangerous Visit Part 2 of 5

Wendy is visiting Saskia. Suddenly the doorbell rings. Saskia opens the door and a fitter is at the door. He should look for a gas leak in the street and check all connections. Saskia leaves Wendy alone for a moment. During this time, Wendy is anesthetized by the stranger. When Saskia finds Wendy, he also holds a cloth in front of her face and anesthetizshe also. 'After waking up, the two young women find that they are tied up and gagged. What is the alleged fitter up to?