The Edge of the Sword
The Edge of the Sword is a Pocket TOS novel – the first novel in the Errand of Vengeance series – written by Kevin Ryan. Published by Pocket Books, it was first released in .

Summary 
From the book jacket
Lt. Jon Anderson is the newest security officer aboard the . He joins the crew at a time of mounting tension between the Federation and the Klingon Empire. Previous battles have been inconclusive, but Starfleet Command fears that the Klingons are gearing up for a major offensive. The Enterprise would be on the front lines of an all-out interstellar war.

But Lieutenant Anderson has a secret: he is actually a Klingon infiltrator assigned to sabotage Starfleet from within. His first mission: kill Capt. James T. Kirk.

Background information 
 The book had a temporary title of Sword's Point. The eBook version was briefly released with it as a cover title.

External link 
 

Edge of the Sword, The