Time Detectives is a spin-off of the Horrible series, quite similar to The Spark Files, though focusing on historical aspects, not scientific. The purpose of the series is to explore historical mysteries in a new, exciting manner. Terry Deary, the author, has also recently announced that he will be writing a similar series called "Wild Words", focusing on the aspects of the English Language. The Time Detectives was fully released in 2000.
The books in the series are:
- The Witch of Nightmare Avenue
- The Princes of Terror Tower
- The Pirates of the Dark Park
- King Arthur's Bones