Earth, 2084. Two global superpowers hover on the brink of war. When the TARDIS is forced to make an unplanned visit to Sea Base Four, the Doctor (Peter Davison), Tegan (Janet Fielding) and Turlough (Mark Strickson) find themselves accused of being enemy agents. While facing a battle for their lives, the trio faces an even greater threat: the Silurians and Sea Devils have formed an alliance. Can the Doctor prevent them from implementing their "final solution" and triggering a war that could wipe out the entire human race? Extras include commentary by actors Davison and Fielding, script editor Eric Sward and visual effects designer Matt Irvine, plus several exclusive "making-of" featurettes.