This episode features the last of the heats, as the battle for the last two places in the semi-finals reaches its climax.The first challenge is a Relay Invention Test, and it's all about teamwork. Split into two teams, each team must create a main course and a pudding between them using turkey for the main, berries for the pudding and a range of fruits, vegetables, herbs and spices. Each team member has 25 minutes to make their contribution to the dishes, but they can't communicate with one another, so each cook must try and work out what the dishes are meant to be from the clues left behind by their teammate and then carry on. Then for the final 15 minutes the team members come together to finish the dishesThe celebrities then remain in their teams and are sent out on their first mass-catering challenge, making lunch at Bisham Abbey National Sports Centre in Buckinghamshire for 80 elite athletes, including members of the Great Britain men's hockey team. With an array of ingredients, the two teams must devise, prepare and serve the lunch, catering for various tastes while creating meat-based, vegetarian and dessert dishes in volume.Then it's back to MasterChef headquarters for the final test. The four celebrities must now cook a faultless two-course meal that will not only be judged by John and Gregg but also by past Celebrity MasterChef champion Lisa Faulkner (2010), previous finalist Christine Hamilton (2010) and semi-finalist Christopher Biggins (2014).With their last chances to impress for a semi-final place, emotions in the kitchen are running high, and the pressure proves too much for some contestants. The celebrity judges deliver some frank and cutting responses to some of the dishes, but others fare much better.This is the last chance for the contestants to earn themselves a semi-final place and come one step closer to winning the title of Celebrity MasterChef 2016. For those who don't make the grade the journey ends here.