The Adventures of K9

The Adventures of K9 was a series of four illustrated paperback storybooks for children written by David Martin and published by Sparrow Books in 1980. The four books feature K-9, the character Martin co-created. Specifically, the stories (according to the Discontinuity Guide website) feature K-9 Mark I and are supposed to take place sometime after the events of The Invasion of Time when the Doctor left K-9 on Gallifrey. The books include prefaces that indicate that K-9 is working on behalf of the Time Lords (which opens the possibility that this could also be K-9 Mark II, depicted in many spin-off media as eventually returning to Gallifrey with Romana who becomes Lord President.

A total of four books were published:


 * 1) K9 and the Time Trap
 * 2) K9 and the Beasts of Vega
 * 3) K9 and the Zeta Rescue
 * 4) K9 and the Missing Planet

Although the general spelling used for the name K-9 is hyphenated, these books consistently use the unhyphenated form, K9. They also suggest that The Doctor's real name might be the Theta Sigma nickname heard in The Invasion of Time.