The final episode of Series 4 of 'Punt PI' sees Steve Punt turning detective and searching for the true site of the Battle of Watling Street where tens of thousands of ancient Britons were massacred by the occupying Roman army but the exact location is unknown. Setting off in a hire car shaped chariot, Punt travels up Watling Street, now known as the A5, which runs all the way from London to Holyhead. Applying his guile and unwavering intuition, he visits three separate sites in the Midlands to examine the evidence. In what becomes an unexpected odyssey, he enlists the help of a pagan psychic, a spiritualist and a military agent to determine where Britain's most epic battle took place. Producer: Neil McCarthy.