K9 Mark III

K9 Mark III was the designation given to the third known version of the robot K9. This version was given by the Fourth Doctor as a present to his former companion, Sarah Jane Smith. The Doctor left him in a crate in her flat in Croydon in 1978 but she did not actually open the crate until she visited Moreton Harwood in December 1981.



Biography
How Mark III came to be built has not been chronicled. Based upon the original K9 Mark I designed by Professor Marius (TV: The Invisible Enemy), and upon K9 Mark II, which the Doctor, in his fourth incarnation, was shown uncrating following the decision by Mark I to stay on Gallifrey (TV: The Invasion of Time), it is likely Mark III was either built by the Doctor, or obtained from the same source from which he got Mark II.

Travels with the Doctor and Adric
After the Doctor had left K9 Mark II to Romana as gift, K9 Mark III travelled with the Doctor and Adric for a short time. (PROSE: Inter-Galactic Cat, Conundrum, Planet of Paradise, Plague World, Just a Small Problem)

Travels with Sarah Jane Smith
The Doctor left K9 for Sarah Jane in 1978 at her the only address he had for her: the home she had shared with her aunt, Dr Lavinia Smith, in South Croydon. Sarah Jane had already moved out of her aunt's home by that time and was travelling extensively. Unaware of its contents, Lavinia stored the shipping crate in her attic until 1979 when she purchased a manor house in Moreton Harwood and relocated there. She had the crate moved to the drawing room in anticipation of Sarah Jane's Christmas visit in 1981 and her own departure for a lecture in the United States. Sarah Jane and her foster-brother Brendan Richards discovered and opened the crate on 18 December 1981. K9 promptly helped Sarah Jane defeat Moreton Harwood's Hecate Cult. (TV: A Girl's Best Friend) K9 and Sarah Jane shared more adventures after this, but only a few have been chronicled. (K9 Annual 1983, et al.)

Circa 1983, K9 Mark III 'lived' with Sarah Jane in Uxbridge; their gate bore a "beware of dog" sign. Sarah Jane dismissed his sense of danger and declined to either stay home or take him with her. As a result, he did not accompany her to Gallifrey. (TV: The Five Doctors) Later, K9 went with Sarah to an archaeological dig in Egypt. (COMIC: City of Devils) In the early 1990s, K9 assisted her in investigating a supposedly haunted house. (PROSE: Housewarming) In 1995, K9 assisted Sarah Jane in contacting Alistair Gordon Lethbridge-Stewart with his large databank of telephone numbers. (PROSE: Downtime) In 1996, Sarah used K9 to hack into records and find Sam Jones' home address, and translate Lost Boy's speech. (PROSE: Interference - Book One)

Breakdown
K9 was briefly possessed by a demonic pig spirit, but was freed when Sarah accidentally electrocuted him. (PROSE: The Sow in Rut) K9 began slowly breaking down and ended up deactivated in a cardboard box in Sarah's attic. (PROSE: Moving On) Later, Hilda Winters had K9 dismantled and analysed. (AUDIO: Mirror, Signal, Manoeuvre)

Sarah Jane was not able to repair K9 after his future technology began to malfunction. She did not show him to anyone else out of fear that revealing his technology could rewrite human history. Having essentially given up on being able to repair him, Sarah Jane began to carry K9's remains around in the boot of her car. (TV: School Reunion)

Sacrifice


In early 2007, while investigating the mysterious jump in student performance at Deffry Vale High School, Sarah Jane encountered a science teacher, John Smith, whose peculiarly happy reaction to meeting her led her to suspect that he was her old friend, the Doctor, (TV: School Reunion) who used the same alias when they first met decades earlier. (TV: The Time Warrior) Accordingly, when she returned to break into the school that night, she brought K9 in the boot of her car. John Smith confirmed that he was the Tenth Doctor and was gleeful to be reunited with not only Sarah Jane, but K9 as well. (TV: School Reunion)

The Doctor was able to repair K9 sufficiently to restore basic functionality restricted to minimal power. He used K9 to identify the intelligence-enhancing oil used in the school's chips as Krillitane oil. (TV: School Reunion)

Rose Tyler, feeling jealous and territorial since Sarah Jane's arrival, mocked K9's design as "... so disco!" the Doctor defensively replied that it was cutting edge in the year 5000. K9 bonded oddly with Mickey Smith who identified himself as another of the Doctor's "tin dogs". This realisation led to Mickey joining the TARDIS crew as a proper companion. (TV: School Reunion)

When Mickey woke K9 to break into the school during the ensuing fight with the Krillitanes, K9 pointed out they were in a car that could be driven straight through the glass doors, which Mickey promptly did. As the Doctor, Rose, Sarah Jane, Mickey and Kenny were cornered by the Krillitanes, K9 rescued them and delayed the Krillitanes until he ran low on power and was left alone. When the Doctor needed to destroy the Krillitanes with their oil, K9 noted his laser could blow open the deadlocked vats, but he needed to be right next to them. The Doctor reluctantly allowed K9's sacrifice. As K9 fatally wounded the Krillitanes, their leader called K9 a "bad dog" — to which he agreed before the school blew up, destroying K9 Mark III as well. (TV: School Reunion)

A melancholy Sarah Jane bid the Doctor farewell and stood in the street as she had done thirty years earlier (TV: The Hand of Fear watching the TARDIS disappear and reveal K9 Mark IV who had Mark III's memories, like a regeneration. The two went off for more adventures. (TV: School Reunion)

Features
Mark III included some improvements over past models. The new mechanics of K9 Mark III included larger wheels and a front and back-wheel drive. K9 also had a brand new coat of paint (this time a metallic-blue) and a handle on the top of the shell to make carrying him easier. (TV: A Girl's Best Friend) Although Sarah Jane indeed carried K9 Mark III to load him into and out of her car, (TV: A Girl's Best Friend) the Eleventh Doctor later implied that Mark IV was not the first to be capable of hovering. (TV: The Power of Three)

Technology
K9 was an advanced computer built in the shape of a robot dog. Among the technology included were a tri-state bus driver, a universal asynchronous receiver/transmitter and holographic memory. He was powered by a self-charging nuclear battery. K9 Mark III was programmed with a wide variety of technical knowledge and scientific data which included, among other things, horticulture. K9 could also provide data printouts of any information requested from his memory banks. (TV: A Girl's Best Friend)

Behind the scenes

 * Only the pilot episode of K9 and Company, "A Girl's Best Friend", was ever produced.
 * In the original outline to K9 and Company, it would have been eventually revealed that K9 Mark III was actually sent by and under the control of the Master, but this element never made it to the screen. The idea of a mechanical companion to Sarah Jane being partially controlled by an enemy was recycled with Mr Smith in TV: The Lost Boy.
 * A publicity photograph of Sarah Jane and K9 Mark III from K9 and Company was displayed in a pan across the 13 Bannerman Road attic at the start of Invasion of the Bane, being only the second use of Classic Era footage in the Revived era, the first being a photo of Brigadier Lethbridge-Stewart an instant earlier.
 * The Sixth Doctor make-your-own-adventure novel Search for the Doctor, published in 1986, features a descendant of Sarah Jane in the 2050s inheriting K9 Mark III. This book was published two decades before School Reunion and the destruction of this K9 unit.