In astrology, the Grand Irrationality is when the planets are all out of alignment and nothing adds up – a pretty fair description of Guy Proud’s life. His job depends on the success of his new ad campaign. He’s sleeping with Nina, the product manager, but he’s in love with Vivienne, who’s French. Murray, his estranged father breaks his leg and has to move in with him, along with his sister Rose, who works out her post-partem depression by obsessively baking cakes.