The Joy Machine

Concerned, the
Federation has sent agents to investigate, but none have returned.
Captain Kirk and the crew of the Starship Enterprise are shocked to
discover the truth: the people of Timshel have succumbed to an insidious
new technology that guarantees every citizen total pleasure, a
soul-destroying ecstasy that has enslaved their entire civilization. 

 Kirk and Spock have faced many threats before, but now they face the
most seductive menace of all: perfect happiness. And the rest of the
Federation may soon fall under the irresistible control of the Joy
Machine.