Christina Trevanion dons a hard hat and descends into a network of little-known tunnels underneath the ancient city of Exeter. Above ground, Ben Cooper's blue team and the reds led by Richard Madley, delve into the antique stalls to unearth treasures to sell at auction in the nearby village of Hele. Can auctioneer Adam Partridge hit a six for the teams, or will they be out for a duck?