It's the semi-finals. Two Michelin-starred Marcus Wareing, formidable chef Monica Galetti and MasterChef's seasoned diner Gregg Wallace step up the pressure in their search for a culinary talent exceptional enough to take the coveted title. After four weeks of fierce competition only the 12 best chefs remain, and the battle is on as they come together for the first time to cook off against each other. Their fate now rests in the hands of the infamous Invention Test. The 12 chefs have an abundant selection of meat and fish, fruit and vegetables and herbs and spices to choose from, but this time all the modern machines have been removed from the MasterChef kitchen. They must go back to basics using just the hobs and ovens - and their chef's intuition - to cook their dishes. As well as having to think on their feet and show off their creativity, their skills and judgment are tested to the limit. In two hours they need to deliver one dish that stands out from the crowd and proves to judges that they have a future in the competition. Marcus, Monica and Gregg choose the best eight chefs to go straight through, leaving the four weakest to cook off in a fight for one of two remaining places in the competition. In the most pressured hour and a half of their lives, the four remaining chefs must cook their showstopper dish, knowing nothing less that perfection is necessary if they want to survive. Only the ten best chefs can go on to battle for the title of Professional MasterChef.