The Starless World

Summary
From the back cover: Captain Kirk encounters Klingons and nocturnal creatures known as Strangers and the sun god himself in a journey of incredible suspense...

Inside the hollow shell of a strange, remote planet Kirk and the Enterprise crew discover a planet within a planet... energized by a white dwarf star... a planet like a lost Eden populated by a race of small, gentle, furred bipeds... a planet falling toward a black hole to spectacular peril and inescapable doom...