Doctor Who: The Newbies Guide
Planet of the Spiders
This is the fifth and final story in Season 11.
The Third Doctor has white hair, a large nose, and tends to dress as a society dandy. He has a love of technology, historical name-dropping, and vehicles. In The War Games the Doctor's people (the Time Lords) sentenced him to exile on Earth. In Spearhead from Space, he was appointed as scientific advisor to UNIT. In The Three Doctors the Time Lords revoked his exile.
Sarah Jane Smith is a journalist who, in The Time Warrior, sneaked into UNIT in search of a story and ended up accompanying the Doctor on a trip to the middle ages. Since then, Sarah has joined the Doctor on his travels and become an ally of UNIT.
Brigadier Lethbridge-Stewart is the commanding officer of the United Nations Intelligence Taskforce (UNIT). He worked with the Second Doctor to defeat threats to Earth on two occasions (in The Web of Fear and The Invasion. In Spearhead from Space, he teamed up with the Third Doctor to prevent an invasion by the Nestene and the Autons. During that story he persuaded the Doctor to work as his scientific adviser, and has worked closely with him ever since.
Sergeant Benton is a UNIT officer. He worked with the Second Doctor to prevent a Cyberman invasion in The Invasion. He has been working with the Third Doctor for several years.
Captain Mike Yates was an officer in UNIT. He has worked with the Doctor for several years, but betrayed both the Doctor and UNIT in Invasion of the Dinosaurs. In that story he was part of a plot to turn back time and give a selected group of people a new start on an Earth undamaged by human activity. He has since been discharged from UNIT.
Recurring and Historical Characters
The United Nations Intelligence Taskforce (UNIT) is an organisation devoted to protecting Earth from extra-terrestrial threats, In The Invasion, the second Doctor teamed up with them to prevent an invasion by the Cybermen. In Spearhead from Space, the third Doctor became their scientific advisor.
There are a number of plot points from previous stories that this story calls back to. There are only two that are important to the plot.
In The Green Death the Doctor took a blue crystal from the planet Metebelis 3. He gave this crystal to his companion Jo Grant when she left UNIT to marry environmentalist Clifford Jones.
In Invasion of the Dinosaurs, Mike Yates was part of a plot to turn back time and give a selected group of people a new start on an Earth undamaged by human activity. His betrayal of UNIT means that he has since been discharged.