Day of the Daleks episode 1 was broadcast 1 January 1972. This story features a British diplomat named Sir Reginald Styles, who organises s peace conference to avert World War III, and invites UNIT. So the Third Doctor, Jo and the Brigadier go over to Auderly House, and interview Sir Reginald Styles. Then UNIT soldiers discover a severely injured guerrilla from the future who has been attacked and take him to hospital. The Doctor then discovers a number of high tech alien devices nearby including a rudimentary time machine and decides to stay at Auderly House to investigate What is going on.
Then Three more guerrilla’s from the future turn up and confront a UNIT Patrol before meeting the Doctor. The Doctor tries to fix the alien device however the guerrillas explain that operating this rudimentary alien time machine could bring some unwelcome guests to Earth. The Doctor learns that the guerrillas are trying to assassinate Styles and tries to change their minds. The guerrillas imprison Doctor and Jo in the cellar. However The Doctor Then Jo manage to escape although Jo soon finds herself in even greater danger….
Meanwhile In the future, the evil Daleks have detected a weak signal emanating from the rudimentary alien time machine at Auderly House and send an evil Dalek supported by Ogrons to attack. Two futuristic guerrillas Anat and Boaz aided by The Brigadier return fire. Elsewhere the Doctor encounters a Dalek before himself Anat and Boaz journey to the 22nd century where they encounter more Daleks and Ogrons. Then The Doctor discovers a rebel factory where he meets the Manager. However the Manager is killed and the Doctor is captured by an Ogron, before being interrogated. The Dalek Controller arrives, and imprisons the Doctor who learns that The Daleks have discovered time travel and intend to invade Earth again.
The Controller explains that at the end of the 20th century, a hundred years of devastating worldwide wars began on Earth, killing 7/8ths of the population. Then the Daleks invaded, conquering the world and using it for raw materials to fuel the expansion of their empire, so in order to survive some humans cooperated with the Daleks.
Suddenly The Rebel Guerrillas under their leader Monia attack the Controller’s base before trying to rescue the Doctor and Jo. The guerrilla rebels then inform the Doctor about Styles nefarious activities concerning the peace conference and his part in the subsequent conflict. The Doctor then finds out that the guerrillas have brought a Dalek bomb with them to Auderly House, and warns them that they will create a predestination paradox by causing the very conflict that they went back in time to prevent in the first place. Meanwhile The Controller, the Interrogator and the Daleks betray each other. Elsewhere the Delegation is evacuated from Auderly House. Then all hell breaks loose as The Guerrillas, the Ogrons, The Daleks and UNIT all converge on Auderly House and confront one another in an explosive finale.