A senior British admiral having had his submarine sunk three time in a row in a war game demands to meet his opponent, imagine his reaction on being introduced to a 20year old WREN. At the height of WW2, an invalided naval officer and a team of WRENs were tasked with creating a game to analyse uboat tactics and teach countermeasures to escort captains; a task at which they were excelled helping to change the course of the battle of the Atlantic.