Yesterday's Son
The Yesterday Saga, Book 1.
The Romulans attack the planet Gateway, where Federation scientists are studying the Guardian of Forever – the mysterious portal to the past.
The Starship Enterprise must protect the Guardian – or destroy it. But Spock has already used the portal to journey to the past. On the planet Sarpedion, 5,000 years ago, Spock knew a beautiful, primitive woman. Now he has gone back to meet his son!
A. C. Crispin
Ann Carol Crispin (1950–2013) was an American science fiction writer, the author of twenty-three published novels. Her writing career began in 1983. She wrote several Star Trek novels, and created her own original science fiction series called Starbridge.
She was married to science fiction author Michael Capobianco.
Star Trek: The Original Series (numbered novels)
Star Trek: The Original Series (numbered novels) consists of ninety-seven books. The current recommended reading order for the series is provided below.
Main series Star Trek: The Original Series