The TARDIS lands near Carbury, and the Doctor and Ace hitch a lift with the local archaeologist who is concerned about a UNIT nuclear convoy that has become stranded near Vortigen's Lake. The U.N.I.T. patrol, commanded by Brigadier Winifred Bambera, is too busy to notice the Doctor and Ace entered the area with old pass cards.
Underneath the lake is an ancient spaceship where the remains of King Arthur are rumoured to lie, along with his sword Excalibur. A group of warriors from a parallel dimension come to retrieve the sword. They all recognise the Doctor - as Merlin the magician, even to the point of knowing that he had a ship of time whose dimensions within defy those without.
Battles break out between an armoured knight and a group of Morgaine's troops and between U.N.I.T. Brigadier Lethbridge-Stewart, learning that the Doctor is involved, comes out of retirement. As the situation gets worse, the Doctor and Ace find their way into the spaceship, and while Ace escapes, the Doctor is attacked, only to be rescued by Brigadier Lethbridge-Stewart.
Morgaine is so desperate to have Excalibur that she unleashes the Destroyer of Worlds. Beofre the final confrontation Brigadier Lethbridge-Stewart knocks the Doctor unconscious and shoots silver bullets into the destroyer, annihilating it.
Regular castAce: Sophie Aldred;
Guest castBrigadier Alistair Lethbridge-Stewart: Nicholas Courtney; Morgaine: Jean Marsh; Brigadier Winifred Bambera: Angela Bruce; Mordred: Christopher Bowen; Shou Yuing: Ling Tai; Ancelyn: Marcus Gilbert; Patrick Rawlinson: Noel Collins (1-3); Elizabeth Rowlinson: June Bland (1-3); Doris Lethbridge-Stewart: Angela Douglas (1,4); Sergeant Zbregniev: Robert Jezek (1); Knight Commander: Stefan Shwartz (2-4); Flight Lieutenant Lavel: Dorota Rae (2-3); Major Husack: Paul Tomany (3); The Destroyer: Marek Anton (3-4, uncredited for 3);
Uncredited cast: Grey Knights: imon Fielder, Mark Jardine, Martin Kennedy, Danny Lawrence; Men-At-Arms: Richard Brennan, Andrew Buttery, Neal Coker, Mark Crosby, Kieth Fradley, Simon Freeman, Carl Harris, Robin Holland, Martin Huighes, Murray McGrough, Peter Novacks, Chris Ponka, Daniel Spicer, Robert Van Copengst, Tony Wayne, Bon Wooding; British UNIT Troops: Howard Buttress, Paul Dore, Graig Gilmans, Laurie Goode, Mark Tony, Stephen Woodhouse; Czech UNIT Troops: Dean Foy, Anthony Hayworth, Andrew Jones, Ken Lee, Peter Oliver, Phil Player, Daniel Spacer; Missile Command Troops: Andrew Bean, Andrew Davoile, Peter Davoile, Gerry Haig, Gerry Lovini, Kevin Maltby, Anthony Moss, Marc Warren;
|BBC 1||682||Part One 1||Wed 6 September 1989||7:35 pm - 8:00 pm||3.1M|
|BBC 1||683||Part Two||Wed 13 September 1989||7:35 pm - 8:00 pm||3.9M||92nd|
|BBC 1||684||Part Three||Wed 20 September 1989||7:35 pm - 8:00 pm||3.6M||95th|
|BBC 1||685||Part Four||Wed 27 September 1989||7:35 pm - 8:00 pm||4.0M||89th|
1: Position is outside the top 100
Repeats (on the BBC)
Black Park, S. Bucks; Castle Cement, Pit Lane, Ketton; Fulmer Plant Park, Cherry Tree Lane, Fulmer, S. Bucks; Hambleton Cross, Hambleton, Rutland Water, Leicestershire; Hambleton Ridge, Hambleton Old Hall, Hambleton Excavation Site, Leicestershire; Little Paston, Fulmer Common Road, Filmer, S. Bucks; Twford Woods, Lincolnshire;
This programme does not have any studio filming
Bloopers and mistakes
Episode 1: In the TARDIS scene, look closely at the roundels - you can see the occasional 'crease', as if the wall was just a sheet hung up behind the console. (The TARDIS walls prop had been destroyed because of Andrew Cartmel's insistence that no more scenes were to be set inside the TARDIS)
Notes and trivia
The episode number for Part One is in the centre of the screen, instead of near the bottom as with other McCoy episodes.
Storm Over Avalon;