Emma Willis hosts the first semi-final, as 12 acts that made it through the blind auditions and the battle rounds compete to impress the judges and win a place in the final. Coaches will.i.am, Tom Jones, Olly Murs and Anne-Marie all return to their infamous red chairs as the acts they have chosen go head to head and fight for their place on their coach's team. The singers that impress their coach the most remain in the competition with a chance of winning a recording contract. Will those that aren't so lucky be stolen by another coach or will they be going home?