Celebrities compete in a contest of culinary skill. After four weeks of intense competition, the best cooks compete in the first of the semi-finals. The celebrities begin with their toughest challenge yet - in a freezing cold field and limited to the use of marquee kitchens, they must cook a feast for 70 guests. Split into two teams, it's a race against the clock as they must design and create four mouthwatering dishes each (meat, fish, vegetarian and dessert) from a selection of ingredients including saddle of lamb, hake, whole salmon and quail. Next it's back to the MasterChef kitchen, where they face an Invention Test with a difference. Each contestant is given their favourite ingredient to work with and, along with a well-stocked larder, has 90 minutes to create a dish that celebrates their chosen ingredient to keep them in the competition. Favourite ingredient choices range from mackerel to scallops, chicken breasts to chicken thighs and haggis.