Picard's old mentor sparks a race to find an ancient code.
Picard's old archaeology professor, Galen, appears and asks for the Captain's help in a research project. When Galen is killed, Picard decides to finish his work. He discovers a mystery involving genetic code in many different species, a clue to the origins of life in the galaxy.
The Cardassians, Romulans and Klingons also race to solve the puzzle, which brings the major powers of the galaxy into the story. The solution reveals that an ancient species seeded the galaxy with the same DNA, which explains why so many species look alike. The episode is an ambitious one about shared origins, and the closing message is hopeful. It is a thoughtful, large-scale science-fiction story.