The Swansea museum store contains everything from a stuffed pigeon to a police car, but can Bendor and Jacky reveal a multimillion-pound lost masterpiece that will not only become a jewel of Swansea museum's collection, but also rewrite art history? Also, a rare appearance at the museum of a giant painting of local coal miners prompts Jacky to re-examine the life of the man who painted them, the renowned Polish artist Josef Herman. She tracks down those who remember him in south Wales.