The Yesterday Saga is a Star Trek: The Original Series mini-series by A.C. Crispin. The mini-series was created by Pocket Books in 1999 when they were re-publishing many Star Trek books. They are sequels to TOS episode: "All Our Yesterdays" wherein Spock was sent back in time via the Atavachron to ancient Sarpieden and met Zarabeth. The Yesterday Saga contains the following adventures:- * Book 1: Yesterday's Son * Book 2: Time for Yesterday