The Tears of the Singers

Summary
From the back cover: Captain Kirk and the Enterprise join the Klingons to avert disaster in the Taygeta V system - where a time/space warp has swallowed a spaceship without a trace.

Spock suspects a link between the anomaly and the inhabitants of Taygeta, semi-aquatic creatures killed for the jewel-like tears secreted at the moment of death.

But a mutinous Klingon officer threatens the vital mission, as a desperate Kirk and Spock race to save the Taygetians, the Federation - and the entire universe.

Information

 * Story is said to take place three years after "Errand of Mercy", placing the adventure in 2270.