David Nobbs writes wonderful comedy because his characters invite odd situations to evolve around them. Here we have Tony (James Nickerson) and Sal (Olwen May), middle-aged, comfortably off, no kids. One morning their doorbell rings. It's Monty and Janey from America, who'd once put them up and to whom they'd said, on parting, "If ever you're passing..." No sooner have they settled them in the best bedroom than the doorbell rings again. And again. Wine is drunk, conflicts arise, accommodations are reached. Funny and curiously credible.