It's July 1981, the Royal Wedding of Charles and Diana. In a small Welsh town where her fifteen-year-old daughter Tammy has organized a street party, Linda Caddock recently made redundant and married to wannabe singer and all-round dreamer Johnny, fears for the future. Neighbour Alan wants her to run off with him. But who will she choose?
The National Gallery in London has flooded, and senior curator Quentin Lester has a dramatic solution. He proposes that the entire collection of priceless paintings should be removed from London and stored in an abandoned slate mine inside a Welsh mountain, as they were during the Second World War. Soon after Quentin is settled in North Wales admittedly more at home in a cave among his paintings than he is with other people he unwittingly sets in motion a series of events that wake up this sleepy, charming town. After mistaking local boy Dylan Hughes for an art history genius, Quentin finds himself in the middle of mayhem.