The Sixth Doctor and Peri take a cruise to New Orleans, in the early 1900's. Peri's befriended a young sick girl named Amy (not that Amy), who's stuck in a wheelchair, and the Doctor is tremendously enjoying the stormy weather. Their holiday is interrupted, though, when they stumble on the corpse of the ship doctor and are found standing over it holding the murder weapon. The Doctor is immediately taken prisoner by the Captain. But since all they can do is hand him over to the cops, the Captain decides to promote him to ship doctor, so he can be tried as a crew member once they reach land (or, by law, thrown overboard if he acts up).
The Doctor is decidedly unhappy with that turn of events and realises that Chief Mate De Requin is most likely behind the whole thing. But he's soon enough summoned to find a cure for Amy, whose condition is getting worse. It doesn't take long for him to realise that "Amy" is a kidnapped mermaid and De Requin is keeping her weak with mercury poisoning (since high levels of mercury are common enough on ships not to be noticed).
Meanwhile, the Captain reveals that he knows something strange is going on, and that his treatment of the Doctor was all a ruse. He and Six investigate, and soon discover that there's a really big hole in the ship right next to where the TARDIS used to be. Just as De Requin is about to murder Peri, the Doctor is dragged to the bottom of the ocean.
He wakes up in a cave (with a big oxygen bubble) and meets a bunch of merfolk, who are looking for "Amy" and Amy's lost baby daughter. The mermaids were captured when they got stuck in a fishing net, and De Requin plans to sell them and become the richest man on the planet. The leader of the merfolk confesses to being the murderer on the ship. After a thorough debate on the Grey-and-Grey Morality of who has the right to kill and who doesn't, the Doctor eventually guides the merman (who grows legs for the occasion) back to the ship, where De Requin has started pointing his gun at people and Chewing the Scenery. Although Amy dies in Peri's arms, her baby is taken back to the bottom of the ocean. So is De Requin.
Tropes
- Be Careful What You Wish For"I will show you as many of my people as you would wish. At the bottom of the ocean."
- Better Manhandle the Murder Weapon: While trying to help the stabbed sailor, the Doctor picks up the knife and is holding it when the captain arrives.
- Bond One-Liner
- Busman's Holiday
- But Your Wings Are Beautiful: Peri, to Amy.
- Call-Back / Call-Forward: See also Hold Your Hippogriffs. This is a reference to Storm Warning.
- Clear My Name
- The Corpse Stops Here: Invoked. The Captain deliberately accuses the Doctor of a murder he knows the Doctor couldn't have committed (the two were together when the victim screamed) in order to coerce the Doctor into aiding him with his investigation.
- Death of a Child: Amy sadly passes away.
- Going Down with the Ship
- Gratuitous French: The Doctor invokes some towards a French crewmate.
- Hold Your Hippogriffs: "This could wake a sleeping Vortisaur!"
- How Dare You Die on Me!: Peri cries this.
- How Many Fingers?
- In Medias Res
- Insistent Terminology: Six being an Insufferable Genius just *has* to correct Peri on whether or not they're on a boat or a ship.
- Insufferable Genius: Six is on a roll.
- The Mole
- Not That Kind of Doctor: The Doctor, yet again.
- Obfuscating Disability: Amy.
- Ooh, Me Accent's Slipping: Jacque's supposed to be French.
- Orphaned Punchline: The Doctor's opening in the adventure....so I said to Livingstone "That's all very well, but the elephant in the gorilla suit has to go."
- Our Mermaids Are Different
- With a dash of Apparently Human Merfolk
- Shout-Out: The Doctor, once being employed via Insane Troll Logic, becomes the ship's Doctor. He does not want to be called Bones.
- Sinking Ship Scenario
- Spy Speak
- Ten Little Murder Victims
- Unstoppable Rage: Peri falls into this in the latter half of the story.
- Villainous Breakdown: The Mole loses his marbles towards the end.
- What Measure Is a Non-Human?
- You're Insane!
