The Daleks Give Chase
It seems in the early episodes, any time something major happened, the Daleks were involved. The Tardis crew had several adventures together before another shake-up in the cast. It started when Barbara discovers the Daleks now have time travel technology and are hunting the Tardis crew for their past 'crimes'. The Doctor is quick to respond but Ian and Vicki have already gone off to explore the sand dunes of the planet Aridius they just landed on.
Ian and Vicki are promptly captured by the locals but quickly rescued by the Doctor. They quickly head off-planet to find a better place to fight the Daleks. The Tardis lands in various places such as an old amusement park, the Mary Celeste (the Daleks frighten all passengers overboard), and the Empire State Building. In one of the oddest moments, the hick Morton Dill is spared by a Dalek who is more bent on extermination the Tardis crew and essentially ignores the ignorant yokel.
While the Tardis crew are scrambling to get away from the Daleks at the amusement park, they are separated and the Doctor takes off mistakenly thinking Vicki is on board. Vicki's only option is to run inside the Dalek ship in hopes of catching up with her friends the next time the Daleks land. While in the Dalek ship, Vicki discovers the Daleks are capable of creating realistic robotic copies of people.
Finally, the Tardis lands on the planet Mechanus and the trio decide it's a good place to make a stand against the Daleks. However it isn't long before they are captured by the planets dominate life form, the Mechanoids. The Mechanoids are robots sent to the planet years before to make it habitable for humans. The group are reunited with Vicki and meet Steven Taylor. When producing the show, it was hoped the Mechanoids would become as popular as the Daleks; it never happened.
The Daleks and the Mechanoids don't exactly get along and a war is started between the two groups. With the Daleks and the Mehcanoids kept busy, the Tardis crew make their escape followed by Steven. Having captured the Daleks functioning time machine, Ian and Barbara bid farewell to the Doctor to head back home. Ironically, the Doctor seems more upset with them deciding to leave than when Susan left.
WHO: Steven Taylor
PLANET OF ORIGIN: Earth's future, though found on the planet Mechanus. 23rd Century
REASON FOR JOINING: Rescued by the Doctor and stows away on the Tardis.
WHO: Ian & Barbara
DEPARTURE LOCATION: Earth, circa 1965 (What's two years among friends)?
REASON FOR DEPARTURE: Took advantage of the Daleks time machine which was able to return them home.
NEXT: Meddling with Time