Casanova (David Tennant) takes us from the decadent streets of 18th century Venice to the salons of pre-revolution Paris, and on to the London court of George II, until a trip to Naples finally breaks Casanova's heart. In the Age of reason and Science, gambling and gallantries, of pleasure and entertainment, Casanova has it all, does it all. In turn he is a violinist, a priest, a gambles, a lottery director and intellectual. He is both peasant and nobleman, rich and poor. But he is one thing above all others - a lover. Sex is Casanova's lifeblood. But he is never casual nor flippant. He loves with total commitment and total sincerity, however temporarily. He sleeps with courtesans, actresses and even a nun. His life is dedicated to pleasure. But one thing eludes him throughout his life - perfect happiness with his one true love - Henriette (Laura Fraser). 44 years later, Casanova (Peter O'Toole), a librarian in a castle, exiled from Venice, is dying. Into his life comes Edith (Rose Byrne), a young parlour maid. Something in Edith ignites the old passion in Casanova and he finds himself regaling her with tales of his adventures. Through Edith, he learns to love the old Casanova again and sends out messengers in search of Henriette. It is one last, desperate attempt to see the woman he loves before he dies.