Doctor Who Discovers

Doctor Who Discovers was a series of educational children's books written by the Fourth Doctor during his time working with UNIT.

The intended title for the series was The Doctor, Who Discovers... but the publishing company misprinted the title, resulting in the author being mistakenly credited as "Doctor Who".

The Doctor completed five books in the series. He began work on the sixth, Doctor Who Discovers Historical Mysteries, but left it unfinished until a robot sent by the publishers from the 64th century invaded the TARDIS to forcefully remind the Fifth Doctor of his contractual obligation; the Doctor therefore resumed investigating the mystery of who killed the Princes in the Tower during the reign of King Richard III of England.

In the course of the adventure William Shakespeare died in the century before his birth, which cause the robot's deadline circuit to malfunction; the robot then exploded. Unable to write about the truth of what happened to Richard and the princes in order to preserve the course of history, the Doctor suggested the possibility of investigating the historical mystery of Jack the Ripper instead. (AUDIO: The Kingmaker)

Behind the scenes

 * Doctor Who Discovers is a reference to a real world book series published by Target Books in the 1970s. As in-universe, they were a series of educational children's books narrated by the Fourth Doctor, of which only five were published despite more being planned.
 * The Doctor's offhand comment that "it was either that or write a novelty cookbook" refers to The Doctor Who Cookbook.