The eight remaining best cooks in the competition head to the biggest naval base in Western Europe to embark on a special mission to serve lunch to members of the Royal Navy on board one of its longest serving ships, anti-submarine frigate HMS Northumberland. The semi-finalists face the enormous challenge of running their own kitchens in two specially constructed catering tents. Split into two teams of four, each team have to create two main courses and a dessert to feed 110 members of the ships company. After judging their food, John and Gregg pick the weakest team to return to the MasterChef kitchen, where they must cook-off against each other in a special Invention Test. One contestant goes home at the end.

It's the last of the semi-finals and it's do or die for the best six amateurs. The contestants have just one challenge to win a place in the final five; to cook an outstanding dish to win-over four of the country's most feared restaurant critics - Charles Campion, Tracey MacLeod, Jay Rayner and William Sitwell. Serving food to these masters of the dining room is a daunting task for the most adept chefs, and these talented home cooks now have to put their skills and palates on the line.