Cryptobiosis (audio story)

Cryptobiosis was the third Doctor Who bonus story released by Big Finish Productions. It was written by Elliot Thorpe and featured Colin Baker as the Sixth Doctor and Nicola Bryant as Peri Brown.

Publisher's summary
There's a ship out there, on the ocean.

She's called Lankester and every year she sails from Madagascar to New Orleans and back again. Every year. Without exception. Regular as clockwork.

Her schedule is never behind. Her cargo is always fresh.

This trip, she has passengers. The passengers have baggage.

And the baggage might just be enough to sink her...

Plot
The Doctor and Peri are sailing to New Orleans aboard the Lankester in 1901 and express their concern for Amy, a wheelchair-using passenger who has not left her room, but Captain Callany assures them that he was given her medication by Dr Blackwell prior to his death. Crawford is found dead, stabbed several times, and Captain Callany has the Doctor taken to the brig by Chief Mate De Requin on account of him holding the bloody knife found by the body. Peri and De Requin argue against him being court martialled on account of him not belonging to the Merchant Navy and Captain Callany subsequently drafts him, intending to have him court martialled once they arrive in New Orleans.

De Requin takes the Doctor and Peri to see to the bedbound Amy, whom the Doctor suspects is being poisoned with mercury. Examining her, he finds that she has inner eyelids and questions her about her legs, which she always had hidden, but he is interrupted when something screams from outside the porthole. Captain Callany confides in the Doctor that he is certain that De Requin is somehow connected to the deaths, although he does not think that he is directly responsible, and that he only accused him so that they could speak without De Requin's knowledge. Whilst the Doctor and Captain Callany are talking, De Requin attempts to murder Peri with mercury.

The Lankester's hull is breached and the impact results in Peri seeing that Amy is a mermaid and has been hiding her tail in a tank of water. De Requin's phial of mercury smashes and he reveals that he intends to sell her to a group for a fortune so that he can start a new life, after which he locks Peri and Amy, whose real name is Amphitrite, inside. Amphitrite explains to Peri how she and her infant daughter, Galatea, were captured in nets and, struggling to breathe, directs her to the hidden tank where De Requin has put Galatea. Peri promises to save her and swears vengeance upon De Requin when Amphitrite dies of suffocation.

The Doctor and Captain Callany inspect the breach in the hull, which seems to have been done with superhuman strength and through which the TARDIS has apparently fallen. The engines give out and the Doctor is pulled down to an air pocket in an underwater cave by mermen where Nereus, Amphitrite's father, tasks him with saving the two mermaids aboard the Lankester, in return for which the TARDIS will be returned. The Doctor agrees, although he realises that Nereus killed Crawford to cover up a visit to the ship and admonishes him for it. Nereus gives himself legs and returns the TARDIS.

De Requin holds Peri and Galatea hostage so that Callany will allow him to take a lifeboat, but the crew have already taken them all. The Doctor returns in the TARDIS with Nereus, who returns to his merman form and has his mermen pull De Requin under the sea when he learns of Amphitrite's death. The Doctor and Peri take Galatea to the underwater cave in the TARDIS and hand her over to Nereus, whom they persuade to rescue the crew of the Lankester from drowning.

Cast

 * The Doctor - Colin Baker
 * Peri - Nicola Bryant
 * Chief Mate De Requin - Tony Beck
 * Captain Callany - Michael Cuckson
 * Nereus - Billy Miller
 * Amy - Naomi Paxton

Worldbuilding

 * De Requin sends McTighe to check on the cargo.
 * The Doctor tells a story about a meeting he had with Livingstone.
 * The Doctor compares the Lankester to the QE2.
 * The Doctor states that his knowledge of marine biology is lacking.
 * Dr Blackwell is the first crew member to die.
 * Mermen live in the seas of Earth.

Continuity

 * The Doctor claims that the smelling salts "could wake a sleeping Vortisaur". (AUDIO: Storm Warning)