Disguise your woebegone depressed spirits. And carry in your search an open bottle of champagne. Knock at the various chamber doors, as it is not done to burst in upon your wife and her companion just to see what filthy minded thing they may be up to. Instead enquire.

"Hey Louise, Louise."

Or in pukka.

"Are you there my dear."

Then enter gently. Even when she has denied her presence. If she is compromised, shake the champagne bottle vigorously and with your thumb on top, squirt the contents liberally into your wife’s companion’s eyes. Then douse Louise and take a good swig yourself.