Mostly Harmless

Mostly Harmless is a novel by Douglas Adams and the fifth book of a four part trilogy, The Hitchhiker's Guide to the Galaxy.

The title derives from a joke early in the series, when Arthur Dent discovers that the entry for Earth in The Hitchhiker's Guide to the Galaxy consists, in its entirety, of the word "Harmless." His friend Ford Prefect, a contributor to the Guide, assures him that the next edition will contain the article on Earth that Ford has spent the last 15 years researching—somewhat cut due to space restrictions, but still an improvement. The revised article, he eventually admits, will simply read "Mostly harmless."