The plot of his illegitimate son Mordred to gain the throne, and Guinevere's growing attachment to Sir Lancelot, threatens to topple King Arthur and destroy his "round table" of knights.

Richard Harris
as King Arthur

Vanessa Redgrave
as Guenevere

Franco Nero
as Lancelot Du Lac

David Hemmings
as Mordred

Lionel Jeffries
as King Pellinore

Laurence Naismith
as Merlyn

Pierre Olaf
as Dap

Estelle Winwood
as Lady Clarinda

Gary Marshal
as Sir Lionel

Anthony Rogers
as Sir Dinadan