Robot Gladiators was the twenty-first episode of K9. It was written by Jim Noble, directed by James Bogle and featured John Leeson as K9 Mark 2, Keegan Joyce as Starkey, Philippa Coulthard as Jorjie Turner, Daniel Webber as Darius Pike and Robert Moloney as Alistair Gryffen.
Darius and K9 go undercover to expose a criminal using illegal robot technology in what he calls "destruct-entertainment". K9 becomes a gladiator and has to face the evil Pain-Maker in a battle to the death. What is the sinister plan instigated by Thorne? K9 also befriends the other Robot Gladiators he sees as cybernetic ancestors, basic androids who have a heart and spirit that touches K9's superior consciousness.
Darius is talking with Freddie "the Entertainer" Maxwell about what he calls "Destruct-entertainment", Robot Gladiators for the discerning lover of mayhem. Freddie has the customers paying hand over fist for video uplinks of his robots fighting in the ring. Even if half of his technology is prohibited by the Department, he dismisses rules as "for the little people". Darius agrees, saying he feels the same way. Freddie asks Darius if he still works for Professor Gryffen. Darius corrects him, saying he quit because Gryffen treated him like dirt. Freddie tells him he heard Gryffen is full of himself, but he has to admire his genius as there isn't one robot in the stables that doesn't carry a bit of his legacy. Freddie asks what Darius brought for him. Darius shows him something he took with him when he left Gryffen: K9. Freddie laughs at K9. Darius, annoyed, asks if he is interested. Freddie says he has a deal.
24 Hours Earlier
In Gryffen House, Darius tells the team about Freddie Maxwell, aka "Freddie the Entertainer", and calls him a two-bit hustler. According to Darius' contacts, he is the mastermind behind Crashclub, old robots modified and forced to fight in an arena for the entertainment of rich "toffs". Gryffen congratulates Darius and hopes that at last, he can put an end to the man who has made a mockery of his Thought Matrix, a revolutionary robotic brain that allows a robot to think for itself rather than to be programmed. When K9 doubts that the thought matrix is that revolutionary, Gryffen explains that while such sophistication may be common in the future before Gryffen came along, robots were nothing more than wind-up toys. Robots moved on thanks to him and they would have moved on even further if the Department hadn't confiscated his technology. Jorjie suggests they alert the Department as Freddie is using banned technology. Gryffen has tried already, but according to June, the Department has got "bigger fish to fry". Gryffen says that he worked long and hard on the technology and he did it for humanity, not to facilitate "revolting" entertainment. As he leaves, Starkey decides to do something about it - undercover work.
Over 24 Hours Later
While K9 communicates to Starkey from inside of a crate, Starkey tells K9 to think of his situation as a holiday. Darius says a really cheap holiday to a slave camp. K9 refuses to speak to Darius, calling him a "traitor" who gave him to a crook like he came from a flea market. Starkey tells K9 that Darius has to do this to find out where Freddie keeps the illegal technology and Darius adds selling him for a bargain made Freddie his pal. K9 needs to find evidence on Freddie if June is to take action. K9's crate is opened by two robots modelled on clowns, Chuckles and Boris. K9 says there has been a mistake and he was supposed to be delivered to the gladiator pens. Chuckles tells him that he's in the pens and they, Chuckles and Boris, are the gladiators. Chuckles says that he and Boris used to be clowns, but since Freddie owns them now they are gladiators. A big powerful robot which Chuckles identifies as the Pain-Maker arrives as he and Boris retreat in fear. He says none of them stand a chance against him. The Pain-Maker pounds their fuel containers. Darius notes it's no second-hand rust bucket and Starkey adds that it's built for combat. Jorjie says that K9 would deal with him without raising a sweat.
Chuckles and Boris show their new roommate, K9, around the place. The walls are the only interesting feature. An alarm activates. Boris is wanted in the pit. He goes down to see Starkey. Darius claimed he is a robotic genius and Freddie hired him on the spot. K9 thanks him, but says it is completely unnecessary. Starkey tells him Darius is in Freddie's office. The minute he finds out how Freddie is getting this illegal technology, they will leave. Starkey tells him that he might like getting to know his ancestors until then. K9 compares it to Starkey being locked up with chimpanzees. K9 says that he can calculate the age of the universe with 98% accuracy, while they struggle to avoid bumping into furniture. Starkey suggests there must have been a K9 which did the same somewhere long ago and that Boris and Chuckles are his past. K9 says he understands what they mean by the 'dim past'.
Darius tells Freddie he doesn't understand how he can swipe tech from the Department and run the place under their nose. Freddie gives Darius lesson 16: "Always be prepared for a swift departure if needed". K9 watches Boris blow up a balloon and let the air out over and over again. He asks Chuckles why he keeps doing it; it's illogical. Chuckles thinks it perfectly logical and says that balloons were his act in the circus and kids loved it. Chuckles wants to go home to the circus. Freddie calls Boris into the ring. Freddie tells an unidentified person in his office that Boris is one of his best and is a real contender and should give his "boy" a challenge.
Boris honks his horn as the Pain-Maker is brought into the ring. Freddie says that K9 should be the one fighting and asks the man if he wants to see K9 fight. When his guest is silent, Freddie addresses the viewers of the match. The Pain-Maker strikes at Boris, who evades the attack acrobatically. He cannot hold out, however, and is destroyed by the Pain-Maker. Freddie says it's not the match he anticipated and he still thinks K9 should have fought. He asks the man, who is Thorne, why he purchased him if he doesn't want to see him fight? Thorne assures him K9's turn will come. Starkey examines the wrecked Boris and K9 asks who did it. Chuckles tells him that he fought the Pain-Maker. When K9 tells Starkey he is changing the plan, Starkey tells him to use his head. They want to shut Freddie down for good and K9 can't arrest him. K9 says he could give him a "good zapping". Starkey tells K9 to just keep up the act a little longer and any minute now Darius will find the evidence they need to shut down Freddie.
At the house, Darius announces he quits. Starkey says he can't. The plan relies on him. Darius says no amount of sucking up to Freddie is going to give him any time to search his office. Gryffen says there has to be some way of exposing him. He tells Darius to think about what Freddie's weaknesses are. All Darius knows is that he likes peanuts and money. Gryffen decides to threaten his finances enough to get him out of his office. Starkey has an idea but needs another undercover operative, Jorjie. After changing into business attire, Jorjie says that the plan won't work. Starkey tells her to just act and speak like her mother. Gryffen advises her to keep the details vague and remember that if she believes it, she is it. Darius advises that if he does suss her, "Lose the heels and make a run for it".
Jorjie arrives in Freddie's office. He tells her to talk to her secretary because he has a fight to organise. She introduces herself as Carolyn Fincher-Jones of His Majesty's Revenue and Customs. He says she's very young to be a tax person, as she calls it. She interprets this compliment as an attempt to influence her. He says he has never given a compliment in his life. He says he's just looking after the office for a friend. She notes his name is on the front door and asks if he is currently engaged in a commercial enterprise. Freddie calls it a hobby. Jorjie asks for the receipts for VAT and threatens to call in more people tax people to investigate. Because of this threat, Freddie goes to get his receipts.
Darius comes through the other door and congratulates Jorjie. In the pens, K9 is dressed up since Chuckles insists he look the part. K9 will not risk Chuckles fighting and being destroyed because he must protect his new friend. Jorjie searches for evidence. Darius decides there's only one place a criminal like Freddie would hide something: the one place he'd never think to look himself. Jorjie finds a data chip under his bowl of peanuts. Starkey arrives as Jorjie uploads it to Gryffen. They hide under the table as Freddie and Thorne arrive. Freddie tells him about the tax woman who just arrived and describes her as trouble. As a CCPC closes the door, Thorne asks if he's sure it isn't Jorjie Turner. He asks about Starkey, and says she has a friend called Darius Pike. They come out from under the table. Thorne tells them not only did he know they were here, he knows everything they have been up to for the past two days; he was setting a trap. Did they think Freddie would believe that Jorjie is a tax woman and Starkey is a robotics expert? He confirms he is working with a known criminal using technology banned by the Department. Thorne announces it's showtime and Freddie addresses the viewers.
K9 is going up against the Pain-Maker. When Darius and Jorjie assure him that K9 will defeat him, Thorne says he hopes so. He knows K9 can regenerate. This is an extremely valuable technology which could be of great benefit to the Department. To secure it, he will force K9 to regenerate. The Pain-Maker is laced with explosive solarmite. After one photon shot by K9, everything inside the bunker will be destroyed except his regeneration unit. The Pain-Maker flashes Boris' handkerchief, angering K9, who prepares to fire. The gang try to warn K9 but Thorne says he can't hear them. The Pain-Maker attacks K9 but he hovers and evades every assault. K9 refuses to fight him. Starkey notes he is too decent to act the way Thorne would, much to Thorne and Freddie's dismay.
Thorne starts the Pain-Maker's self-destruct sequence. It detonates. Thorne orders the CCPCs to recover anything they can find. K9 arrives having escaped the explosion. He explains that although solarmite would damage him, the only explosion capable of destroying him is his self-destruct. Freddie asks when he and Thorne are getting together to build his new arena. Thorne says he was never here. Thorne leaves and Freddie follows him. Darius offers K9 peanuts and he refuses.
Back at the house, Gryffen finds no damage to K9 from the explosion. No one understands how Thorne knows about K9's regeneration unit. K9 suggests Thorne has sources of information beyond what they know about him. Darius comes in with a call for K9 from Chuckles and Boris, who has been rebuilt. They are going back to the circus and he thanks them for shutting down Crashclub.
At the Department Mobile HQ, Thorne speaks with Lomax. He assures him the Department will have no recorded connection with Crashclub. Freddie will take the whole fall. K9 knows of Thorne's intent to take his regeneration technology, which will make acquiring it harder, but not impossible. They will get it and their plans will succeed. Lomax orders him to use all the powers at his disposal. Thorne assures that he intends to.
- K9 Mark 2 - John Leeson
- Starkey - Keegan Joyce
- Jorjie Turner - Philippa Coulthard
- Darius Pike - Daniel Webber
- Professor Alistair Gryffen - Robert Moloney
- Thorne - Jared Robinsen
- Freddie Maxwell - Gareth Harris
- Chuckles - Remi Broadway
- Boris - Michael Donnet
- Lomax - Peter Kent
- CCPC - Eugen Bekafigo
- CCPC - Jason McNamara
- CCPC - Josh Norbido
- CCPC - Tyler Rostedt
- Writer - Jim Noble
- Director - James Bogle
- Producers - Penny Wall, Richard Stewart, Simon Barnes
- Executive producers - Jim Howell, Grant Bradley, Steve Robbins
- Associate producers - Bob Baker, Paul Tams
- Supervising producer - Dale Bradley
- Co-Executive producers - Mark Blythe, Sam Tromans
- Line producer - Pam Collis
- VFX Director - David Napier
- Series Production Designer - Jon Dowding
- Episodic Designer - Adam Head
- New K9 Design by - Paul Tams, Alex Kubalsky
- Series Director of Photography - Ben Nott
- Episodic Director of Photography - Tony O'Loughlan
- Music by - Christopher Elves
- K9 theme music by - Michael Lira
- Editor - Patrick Stewart
- Casting - Faith Martin and associates
- Episodic casting - Lisa Maloney
- Drama/Dialogue coach - Peter Kent
- Story Producer - Greg Walters
- Script Adaption - Michaeley O'Brien
- Production Accountant - Pru Donovan
- 1st Assistant Director - Peter McLennan
- Script Supervisor - Sue Ketchington
- Costume Designer - Joanne Thompson
- Makeup Designer - Sharon Robbins
- Puppeteer - David Pawsey
- Location Manager - Charles Boyle
- Sound Recordist - Ian Grant
- B Camera Operator - Dan Maxwell
- Gaffer - Steve Monk
- Key Grip - Billy Harmer
- Special thanks to - Space Furniture, Shredox, J. Barbour & Sons Ltd, Heath Williams at Firefly Lighting, Videopro
- Safety Supervisor/Stunt Coordinator - Danny Baldwin
- Transport Manager - Alister Ward
- Unit Manager - Graeme Suhr
- Post Production Facility - Cutting Edge Australia
- Head of Post Production - John Lee
- Sound Design - Warren Pearson
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- This is the first episode of K9 in which June Turner does not appear, although she is mentioned.
- This episode is similar in premise to the Torchwood episode Combat.
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- Thorne says he knows about K9's regeneration unit. (TV: Regeneration)
- Robot clowns previously appeared in TV: The Greatest Show in the Galaxy.
Home video releases
This episode is featured in the following DVD sets:
- Series One complete box set, released in Australia on 29 September 2010. 
- K9: Series 1: Volume 2, containing episodes 13–26, released in the UK and US on 18 April 2011. , 
- K9: Ultimate Collectors Edition, containing the full first series, scheduled for release in the UK on 11 June 2011.