MasterChef Series 13 Episode 21 Episode 21 ( Air Date 2017-05-05 ) Genre Reality category. Overview "It is the last of semi-finals, and the remaining six amateurs attempt to win a place in the MasterChef finals. To win their place in the final five they must cook an outstanding dish for four of the country's most feared restaurant critics - Amol Rajan, Tracey MacLeod, Jay Rayner and William Sitwell. At the end, John Torode and Gregg Wallace decide who to take through to finals week.".