A secret lab. A missing wife. A monstrous truth buried in memory.

Deep beneath the Arizona desert lies Subterra-9, a classified government facility conducting unauthorized genetic research. Dr. Grant Caldwell and his brilliant wife Elena were part of its most dangerous experiment yet: merging human DNA with bat genomes to unlock new biological frontiers.

Then Elena vanished.

Now, something stalks the underground halls. Co-workers disappear. Systems fail. The survivors whisper about a shape in the vents—fast, brutal, and eerily familiar.

When Grant discovers Elena injected herself with the experimental strain, his mission becomes clear: find her before the government terminates her—and before her altered mind forgets what it means to love.

But what if she's already gone?

And what if something worse came back in her place?

From bestselling author Dr. Rabea Hadi comes a haunting thriller that will stay with you long after the last page is turned.
Project Nightfall blends cutting-edge science fiction, chilling horror, and psychological suspense into a relentless race.

The echo is waiting.