The Last Threshold: A Hard Science Fiction Mystery Thriller (Book 3): The Erasure Protocol Trilogy, #3

Dr. Mara Ellison believed the greatest challenge facing humanity was uncovering the truth about an ancient civilization that vanished millions of years ago. She was wrong.

The discoveries made across thirty-seven distant worlds have revealed that humanity is part of a design far older and more complex than anyone imagined. Every civilization that came before reached the same point in its history. Every one of them made the same final decision.

Now humanity is approaching that moment.

As unexplained phenomena spread through the network left behind by the ancient builders, Mara and the crew of the Aletheia race to understand a system that has silently shaped civilizations across the galaxy for millions of years. With governments divided, trusted allies questioning one another, and evidence pointing toward a future no one is prepared to accept, every answer raises the stakes.

The closer Mara comes to understanding the purpose of the ancient network, the clearer it becomes that the greatest danger is not the technology itself, but the choice every civilization has ultimately faced. Whatever compelled them to abandon everything they had built has begun to confront humanity as well.

As time runs out, Mara must decide whether the future of the human race depends on following the path of those who came before—or finding the courage to choose a different one.

The answers waiting beyond the last threshold will determine not only humanity's future, but whether its history has ever truly belonged to it.