Heat Three

With a place in the semi-finals at stake, the bakers face two tough challenges. First, a test of baking know-how in the technical challenge, where they try to master Mary's recipe for marble cake. They must then make a splash in the show-stopper challenges as they bake and present a selection of impressive under-the-sea-themed biscuits. Who will win over formidable judges Mary Berry and James Martin to secure a place in the semi-final?