For millennia, the Makers' Life Probes explored the farthest reaches of space in search of the secret behind faster-than-light speed. In the 22nd century, the people of Earth made a pact with this far-flung civilization—all of the Makers' intelligence in exchange for help in their mission.
Three hundred years later, descendants of the original Procyon expedition have returned to Earth in a starship. They find a world that has forgotten the generations-old contract.
No matter. The returning colonists have overcome far greater obstacles in their single-minded drive to redeem a promise made before any of them were born...