It follows the adventures of the crew of the Paradox, led by Captain Thrice, on their quest to find the legendary Lavender Castle and prevent Big Bad Dr Agon from destroying it.
The crew of the Paradox include Captain Thrice, his walking stick which was brought to life during a previous encounter with Lavender Castle, Isambard (Engineer), Roger (Pilot), Lyca (Doctor), Sir Squeakalot (Ship's robot) and Sproggle (Navigator).
Lavender Castle provides examples of the following tropes:
- Batman Can Breathe in Space
- Big Bad: Dr Agon
- Bond Villain Stupidity: Displayed by Dr Agon in High Moon.
- Clip Show: The last episode of Series 1, Birds of a Feather, which has the villains recalling how they've tried and failed to defeat the Paradox.
- Deadpan Snarker: Captain Thrice's Walking Stick, which was given life on Captain Thrice's previous trip to Lavender Castle.
- Deus ex Machina: Lavender Castle itself sometimes saves the crew from otherwise inescapable situations.
- Eyes Do Not Belong There: Captain Thrice has a third eye on his nose.
- "Freaky Friday" Flip: Brought about by a cosmic cloud in Cloud of Chaos.
- Genius Loci: Lavender Castle might be one of these.
- Instrument of Murder: Dr Agon uses a laser trumpet in the first episode.
- Meaningful Name: Dr. Agon. Get it?
- Mental Time Travel: In "A Stitch in Time".
- No Sense of Direction: Sproggle, who often has trouble telling his left from his right.
- Percussive Maintenance: Isambard often applies this to the Paradox's engine.
- Pirate Parrot: Short Fred Ledd's robotic parrot Tin Lizzy.
- Reports of My Death Were Greatly Exaggerated: Said word for word by the Guardian in Raiders of the Planet Zark.
- Space Pirates: Short Fred Ledd and his robotic parrot, Tin Lizzy.
- Star Fighter: Roger's old craft, the Firefly, which appears in The Lost Starfighter and Lost in Space.
- Star Killing: Dr Agon does this.
- Third-Person Person: Sproggle
- Unrealistic Black Hole: In "Birds Of Prey".
- Verbal Tic: Tin Lizzy often has a habit of copying what Short Fred Ledd is saying, which Short Fred Ledd finds really annoying.