The next 12 contestants face a fresh set of challenges based on the games Mensa use to measure IQ, including a code-breaking challenge so complex that the youngest contestant, student Rosie, really struggles with - and not just because she may never have seen a landline phone before. By the end of the episode, only three will earn a coveted place in the Oxford finals.

The final 12 players are faced with a high-pressure quickfire round, where they must solve a complex maths game to work their way out of a maze. After some surprising drop-outs, the remaining players face each other in a mind-bending memory game based on the periodic table.