Battlefield

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.

• Brigadier 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, Mark Warren;