The Doctor and his companions Nyssa, Tegan and Turlough are in Calcutta, visiting for the Doctor's favourite pasttime. Cricket. But before they can see the match, a creature-that-was-once-a-man attacks the crowd, and bites Nyssa. Nyssa contracts what the Doctor thinks is rabies, and the TARDIS gets stolen onto a private train! A chase occurs, obviously.
But in the jungles of India, the undiscovered country, they find a literal beast with emerald eyes, it spreads darkness where it goes, and will mean the death of everybody it comes across.
The Emerald Tiger contains examples of the following tropes:
- Big Damn Heroes: Tegan rides in on an elephant to scare off the monsters and save the day.
- Body Horror: Nyssa's transformation is extremely painful and involuntary.
- Call-Back: Nyssa mentions Terminus.
- Call-Forward: Turlough mentions that he doesn't like caves.
- Chekhov's Gun: Giving Tegan the TARDIS key.
- Continuity Nod:
- When Turlough grumps about not liking the reason they're in Calcutta being a cricket match, the Doctor mentions he should have a word with the Brigadier about his education.
- Nyssa asks the Doctor if he's playing himself, like at Cranleigh Hall.
- Nyssa mentions she's had a history researching diseases.
- Disney Death: Nyssa. Having reintroduced the character at a point after her televised departure, Big Finish are clearly delighting in teasing the very real possibility that they could permanently kill off an original series companion.
- Distinction Without a Difference:Tegan: Your tiger is going to eat a friend of mine!Lady Forrester: No. Kill him, yes. Eat him? No.
- Drives Like Crazy: The Doctor is not the world's best driver.
- Fountain of Youth: As a side effect of the healing energy given to Nyssa at the end of the story. Not only is she cured of the werebeast virus, she is de-aged several decades. Tegan notes she looks exactly as she did when they parted company in "Terminus".
- Friendship Moment: The Doctor is overjoyed to find out Tegan isn't dead, and tells her that the universe just wouldn't be as interesting without her in it. Naturally, she agrees.
- Go-to Alias: The Doctor introduces himself as "Dr. Smith" to a hot air balloon pilot.
- Hungry Jungle: Thanks to an alien entity controlling most of the flora and fauna.
- Limited Wardrobe: Turlough averts it for once, swapping out his school uniform (something he never did in the series) in trade for a three piece suit in order to better fit in during the time period.
- Like You Would Really Do It: Killing off Tegan fools no one.
- Long-Lost Relative: Jahn is actually Jonathan, Lady Adela's son whom she thought died in the jungle as a toddler.
- Mega Manning: Djahnn devours Dawon and Narayan in order to add their power to him.
- Mega Neko:
- Jonathan: Bigcat on the water.
- Mix-and-Match Critters: The substance the Emerald Tiger is made of functions as a medical adhesive, which rearranges biological makeup to make healthier ones. Accidentally creating ruby-beetles, and flying frogs and the such.
- Nubile Savage: Jonathan is a male version, running around the jungle in a loincloth, and Tegan describes him as having a "surfer's build".
- Obfuscating Stupidity: Dawon spends some time pretending to be just a dumb animal, if an extremely exotic one.
- O.O.C. Is Serious Business: The Doctor is distraught enough over Tegan's demise that he rounds on Turlough in a blunt fury when he suggests not putting themselves into more danger, and goes so far as to tell him to leave the TARDIS if he doesn't follow orders.
- Our Werebeasts Are Different: Victims of the Emerald Tiger can turn themselves into giant tigers, but with each transformation returning to human form becomes more and more difficult.
- Quintessential British Gentleman: The Doctor brings the TARDIS team to India, 1926 ... for a cricket match.
- Shout-Out:
- Tigers, snakes called Kaa, bears called Balloo, India, and jungles.
- Tegan refers to the giant tiger creature as Pussy Galore.
- According to the bonus material, all not-TARDIS crew characters are named after adventure book writers like Edgar (Rice Burroughs), etc.
- Tegan: Me Tegan, you John!
- The Doctor warns against falling over a makeshift bridge with crocodiles under it, reminding the crew of "Captain Hook".
- Third-Person Person: Jonathan, functioning as a Tarzan homage.
- Unobtanium: The Tiger Emerald is a substance called Hemogonite which can alter genetic makeup in order to heal wounds better. It crash-landed onto Earth millennia ago.
- Vindicated by History: The inverted of this, really. Darwin gets invoked, and it's pointed out how peers view him as a madman.
- Vitriolic Best Buds: Tegan and Turlough, even when one has just come back from apparently certain death.