Hire the cheapest contractor, and (usually) get even less than what you hoped for. Basil and Sybil decide to block off a couple doors and put in a couple new doors instead - the notoriously bad construction company in town, run by airhead Mr. O'Reilly, is hired by Basil because they work for cheap. All hell breaks loose when the Fawltys go away for the weekend, during which time O'Reilly's men do great damage to the hotel lobby. The incomparable (and always underweight!) David Kelly does splendidly as unscrupulous O'Reilly, who has about as much knowledge of construction as a garden gnome. This episode shows Sybil at her most caustic, "nest of vipers" self - Basil and O'Reilly don't stand a chance against her when she catches a glimpse of the remodel. John Cleese has stated that this episode is probably the weakest of the series - but there really is no weakness. The situation itself was perhaps not one that would evoke much comedy, but it has its great moments, such as the bit where Manuel gets attacked by Basil when he can't figure out how to get into the dining room because the door is missing...then, as usual, the Major comes in and puts the icing on the situation, wondering what's going on. BASIL: "Well, I was silly enough to leave the hotel for a few minutes."
Review of The Builders
