Doctor Who/Recap/S13/E01 Terror of the Zygons

""Oil? An emergency? Ha! It's about time the people who run this planet of yours realised that to be dependent on a mineral slime just doesn't make sense.""

- The Doctor doesn't agree with the Brigadier's assessment.

The TARDIS arrives on Earth following the Brigadier's summons. UNIT are investigating a series of attacks on North Sea oil rigs from a temporary base in the Scottish village of Tulloch. The Doctor discovers that the attacks are the work of a giant cyborg controlled by an alien race called the Zygons from their ship beneath Loch Ness. The Zygons can imitate the form of other life-forms whom they have imprisoned on their ship, and are currently impersonating many of the village locals in order to infiltrate the UNIT base.

The Zygons plan to use their shapeshifting abilities to take over the world as a substitute for their own dead planet, but the Doctor releases the prisoners and destroys the ship, killing all but one of the Zygons. The survivor, Broton, makes his way to London disguised as the Duke of Forgill, planning to destroy a World Energy Conference using the cyborg, known as the Skarasen, and use this show of strength to persuade the world to give in to his demands. However, before he can do so, he is shot by UNIT, and the Doctor feeds the tracking device to the Skarasen. With no more control, the Skarasen returns to the only home it knows - Loch Ness. Harry decides he's had enough of this time-travel lark and remains on Earth while the Doctor and Sarah depart for adventures new.

Tropes
""You have to step out on a balcony from time to time and wave a gracious tentacle.""
 * Balcony Speech: Lampshaded by the Doctor


 * BBC Quarry
 * Bookcase Passage: Sarah Jane Smith finds a passage behind a bookcase leading to the alien spacecraft under Loch Ness. She activates the opening mechanism by pulling out a book, which she could only reach via portable steps fetched for her by Broton, then disguised as the Duke.
 * Bond Villain Stupidity: Despite constantly assessing the Doctor as "too clever" and "dangerous," Broton and his cronies make only halfhearted attempts to kill him, and never stick around long enough to be certain.
 * Dude in Distress: Both Harry Sullivan and the Doctor end up being kidnapped in this story, and for once, it's not the girl companion—Sarah Jane even rescues Harry Sullivan at one point!
 * Everything's Louder with Bagpipes: Angus the landlord plays "Flowers of the Forest" on the bagpipes. It turns out to be an omen (of sorts).
 * Impaled with Extreme Prejudice: The Zygon impersonating Harry tumbles off the haystack after lunging at Sarah and is promptly skewred with his own pitchfork.
 * Loch Ness Monster: "THE Loch Ness Monster!"
 * Man in a Kilt: The Brigadier.
 * Also the Caber, the Duke's "Highland Games Champion" manservant.
 * Only Known by Their Nickname: "The Caber." The Duke (actually Broton in disguise) tells Sarah that the Caber's real name is "very Gaelic" and she probably couldn't pronounce it.
 * Organic Technology
 * Put on a Bus: Harry Sullivan decides he's take the train back to London.
 * Tap on the Head: The Zygon disguised as Sister Lamont rather savagely bonks a UNIT soldier over the head with a rock. Somehow he survives without getting his skull split open.
 * Voluntary Shapeshifting: The Zygons have the ability to transform themselves to resemble humans they've abducted.
 * The X of Y
 * What Could Possibly Go Wrong?: Sarah Jane only agrees to get back into the TARDIS this time if the Doctor promises they'll go straight to London, five minutes before he left, as he confidently stated it could. He guarantees it. We all know this can't possibly go awry...