Lupin is hired by his old friend Gaston to steal a certain painting from the vault of Mr. B, a compulsive art collector. The painting is a Picasso forgery ostensibly painted by Gaston's grandchild. Lupin succeeds in his heist, but he and Jigen end up being chased by the DGES. Lupin discovers that the painting is the hiding-place for a notebook containing information about sensitive crimes hushed up by the French police, evidence which would topple a number of high-level persons if its contents went public...