Princess Principal/Recap/S1/E03 Case 2 Vice Voice

Quoting from Wikipedia: "It is revealed that Ange became a spy so she could cross the wall and reunite with Princess and smuggle her out of the country. However, Princess tells her that her desire to be Queen was genuine, as she wants to tear down the London Wall and create a world where they both can live together without having to hide. Ange agrees to carry out her wish. Ange and Dorothy then receive a mission to board the HMS Gloucester and recover stolen printing plates. They decide to use Princess as way to board the ship, though Beatrice protests her participation in the mission. However, Beatrice's voice becomes odd as she shouts, and she flees in embarrassment. Princess reveals that Beatrice had been experimented upon by her father, and her vocal cords were replaced by machinery. With Princess and Dorothy's help, Ange manages to sneak onto the airship, with Beatrice inadvertently following her. Ange assaults the agent transporting the plates but is injured and insists that Beatrice take the plates and leave her behind. Beatrice instead uses her mechanical voice-box to impersonate the agent's voice and call off the guards, giving her and Ange the time to escape together. Realizing that Ange cares as much for Princess as she does, Beatrice decides to join the spy team."


 * Air Vent Passageway: Dorothy makes use of one in Case 2. Unlike the traditional shiny steel with a rectangular cross-section, this is basically a giant brass pipe.
 * Boom! Headshot!: The Princess accidentally blows the head off a marble bust with a shot from a gun disguised as a pen.
 * Counterfeit Cash: Part of the plot of Case 2. The Kingdom has stolen the plates for Commonwealth currency and plans to print vast quantities in the colonies, with the goal of undermining the Commonwealth economy.
 * Potty Emergency: Dorothy fakes one in order to get aboard an airship that the team needs to search.
 * Shoe Phone: Princess manages to accidentally release the safety and fire a one-shot gun disguised as an ordinary pen.
 * Something Only They Would Say: Inverted. Ange is able to provide Beatrice with information that lets her convincingly impersonate a "trapped officer" to one of the crew of the warship they're on.
 * Wall of Weapons: Dorothy reveals one hidden behind a section of wall in the "clubroom".