Livia Pertini is 79 and struggling to interest her granddaughter Rosa in the age-old recipes of her home, Fiscino, a tiny hamlet on the slopes of Mount Vesuvius. These recipes reveal the unimaginable hardships of the Second World War - mouse stew, dandelion frittatas - but also tell the story of a young, vivacious Livia. Naive and already war-weary, James Gouding takes up a British Field Security Service position in Naples, 1943. What he doesn't anticipate is that this involves a limited menu of fried Spam fritters and interrogating the would-be Italian fiancees of members of the armed forces. James's chance at true heroism arrives when a German tank is sighted and he is caught in its path. However, it is the imperious and dogmatic Livia who opens the hatch and yells at him to stop being such an idiot. Livia gladly becomes cook, translator and general factotum to James. The two begin to fall in love, knowing that Livia's husband away at war and James's girl back home will mean they can never acknowledge their passion. But the eruption of Vesuvius triggers a chain of explosive events that will force the two to flee behind enemy lines and will alter their lives immeasurably.