Giacomo Casanova, an elderly librarian (Peter O'Toole) in a castle in Bohemia, has a lot of memories, which he shares with Edith (Rose Byrne), a young servant. This takes us into the world of the young Casanova (David Tennant), a dashing Venetian chancer and outlaw who tumbles the ladies of Europe in an astonishing career.  But for most of his wandering life, Casanova carries a torch for Henriette (Laura Fraser), who was snatched from him long ago by his rival Grimani... and for fifty years, Henriette does her best to look after Casanova, even though in all that time they never meet again.