Art detective Philip Mould and journalist Fiona Bruce try to prove a painting hanging in a Welsh Castle is by celebrated French Impressionist, Pierre Auguste Renoir. Nicky Philipps, a portrait artist renowned for her pictures of the Royal family, has asked the FAKE OR FORTUNE? team to investigate a mysterious painting which hangs on the walls of Picton Castle - once the family's ancestral seat. The work was bought in the 1930s by Nicky's Great Grandfather Sir Laurence Philipps, who believed it to be by Pierre Auguste Renoir. But for 50 years the painting has been dogged by doubt and two powerful art world authorities can't agree whether it's genuine or fake. Nicky believes in the painting because her late Aunt Gwen told her a tantalizing story that it came from Claude Monet's studio in Giverny. She said it was a gift from Renoir to Monet after they had been working together. But family legend isn't enough to convince the art world's toughest judges - the team must find hard evidence. The trail takes Philip to the River Seine at Argenteuil, where Renoir and Monet painted side-by-side. Simultaneously, Fiona picks up the provenance trail at Monet's House in Giverny, where she tries to find proof the painting was once hanging among Monet's art collection. Meanwhile, art forensics expert, Aviva Burnstock, invites Philip to Berlin to see if cutting-edge technology can determine whether the pigments in Nicky's painting match up to those listed by Renoir himself. She uses a special camera to see through the canvas, revealing a remarkable piece of evidence that's been hidden from view. Along the way Fiona discovers that the picture is caught between two rival art world authorities - The Bernheim Jeune Gallery and the Wildenstein Institute - who both believe their word is the last word when it comes to Renoir. When the dust settles, will Nicky's painting be fully accepted as a genuine work?