Joe Lycett hosts the semi-final, as the four remaining sewers go global, taking on garments and techniques from around the world. Firstly, the semi-finalists must follow a pattern like none they have encountered before, as judges Patrick Grant and Esme Young ask them to make a pair of Indian dhoti pants. Using a process based on the centuries-old tradition of folding and draping large rectangular pieces of fabric, these wide-legged, heavily pleated trousers prove a perplexing, visually striking, proposition.Next up, it is the transformation challenge, as the sewers take on a garment from West Africa, the Dashiki. This colourful, strikingly patterned men's tunic must be transformed into a brand new outfit in just 90 minutes, making imaginative use of the Dashiki's distinctive, bold print.For their final challenge, the made to measure, the sewers take on the fiendishly tricky high end Japanese couture technique of origami. Tasked with creating an origami top for their model, the sewers must sculpt dramatic, arresting garments, drawing on the ancient art of paper-folding. It proves to be a pain-staking process, pushing the sewers pattern drafting, fabric-handling and precision sewing to new heights. But only three of these four incredibly talented sewers can make it through to the grand final.