On the day that his life begins to fall apart, Paul Slippery frantically tries to find his friend and patient, Nobby, before the man can indulge in a potentially disastrous dose of Viagra. Meanwhile, Paul's wife, Estelle, loses her job but finds a new one in a surprising place.
Paul's plans for an erotically charged dinner with Estelle take a detour when he gets entangled in his son Daniel's two-timing love life, and the father of Daniel's girlfriend seeks treatment for a rather embarrassing malady. Across town at a business lunch, Paul's colleague, Pilfrey, takes a more-than-professional interest in Estelle.
Still smitten with Estelle, Pilfrey exhibits increasingly bizarre behavior at the most inopportune time imaginable -- just as the practice prepares for a National Health Services inspection. The situation doesn't get any better when Pilfrey mistakes Paul's son for the government inspector.
In a desperate attempt to revive his sagging sex life, Paul surreptitiously tries to ply Estelle with an herbal aphrodisiac. Estelle, however, has other things on her mind -- namely, a speech about mothers in the workforce that her boss has bullied her into delivering.
Paul becomes convinced that Estelle is having an affair, and his colleagues become convinced that he has hit the sauce too hard. Later, by drowning his sorrows over the supposed affair and having a most awkward encounter with Surinder, Paul unwittingly gives them plenty of reason to worry.
When sons Rory and Daniel decamp to their own flat, everyone in the Slippery household begin to reassess their lives. Paul, for his part, agrees to hypnotherapy at the hands of Pilfrey, whose guidance proves anything but benign. Estelle entertains an odd proposition from her boss.