To Reign in Hell: The Exile of Khan Noonien Singh
To Reign in Hell is a Pocket TOS novel – the third and final novel in The Eugenics Wars series – written by Greg Cox. Published by Pocket Books, it was first released in hardback in .

Summary 
From the book jacket
At last – the untold chapter in the history of Star Treks most notorious villain, KHAN. Searing and powerful, To Reign in Hell masterfully bridges the time period between Khan Noonien Singh's twenty-third-century revival in the Original Series classic episode  and his unforgettable return in the acclaimed feature film .

What truly transpired during Khan's long years of exile on the forbidding world of Ceti Alpha V, before the tyrant escaped to embark on a murderous campaign of vengeance against Admiral James T. Kirk? What horrific trials spawned Khan's insane lust for revenge?

Haunted by the memory of Khan's bitter accusations, Kirk now revisits Ceti Alpha V to discover for himself what ultimately drove Khan to madness. There, buried beneath the desolate surface of a dying planet, Kirk and his allies find the untold story of their greatest foe – and of the woman who loved him: Lieutenant Marla McGivers of Starfleet.

Along with Khan's genetically-engineered followers from the twentieth century, Khan and Marla are left on Ceti Alpha V with the hopes of building a new life together. Although the planet is savage and untamed, full of deadly predators and unexpected hazards, Khan dreams of carving out an empire even greater than the one he once ruled on Earth.

But when catastrophe strikes, laying waste to the entire world, Khan and the others find themselves trapped in a desperate struggle for survival. Now Khan must use every ounce of his superhuman strength and intellect to wage a fearsome battle against the planet, his people… and the growing darkness in his own soul.

Background information 
 The novel spans the gap between Khan's marooning in  and his rediscovery in . Author Greg Cox knew that this novel would be the obvious follow-up after filling in Khan's backstory in the Rise and Fall duology, but had only a few lines of dialogue in the movie to go on, considering it "[the] big challenge: Could I get an entire book out of a few dozen people stuck on a barren rock for fifteen or so years?" ()
 Cox noted that this third novel in the series strikes a very different tone: "grimmer, more tragic, and less rife with opportunities for cute fannish in-jokes and cameos." Early on, he determined that there was no place for the involvement of Gary Seven and Roberta Lincoln (who had been central to the previous duology), and appearances by known Trek races would go against the idea that Khan and his followers had been alone for the fifteen years set out. ()
 He also felt it was important to give McGivers a central role in the novel: "In my head, I always thought of her storyline as 'The Rehabilitation of Marla McGivers'. […] My goal was to toughen Marla up some, and give her more of a spine, while still remaining consistent with the character we met in the original episode." ()
 The original title of the novel was A World to Win, based on the final line of dialogue by Khan in ; however, Pocket editor Marco Palmieri suggested using the John Milton line spoken by Kirk at the end of the episode instead. ()
 Marla McGivers refers to the events of , and  whereas Sulu recalls those of .

Characters 
Khan Noonien Singh
Marla McGivers
James T. Kirk
Spock
Leonard McCoy
Hikaru Sulu
Joaquin
Joachim
Harulf Ericsson
Leader of the Exiles, seeking to end Khan's rule; former foreign operative of the Great Khanate on Earth during the Eugenics Wars
Astrid Ericsson
Daughter of Harulf and Karyn Bradley, leader of the Exiles c. 2287

References 
Ceti Alpha star system

Ceti Alpha V

Ceti Alpha VI

External link 

Novels