Books six, seven, and eight in the John Decker series.

Black Tide: In the last months of World War Two, the German Navy premiered a new and terrifying weapon: a submarine of incredible range that could strike anywhere, anytime. And it did, prowling the shipping lanes night and day, striking fear into the Allies. It was just what Hitler needed to turn the tide of war.

Until it disappeared without a trace.

Now, more than seven decades later, the wreck of a previously unknown U-Boat has been found off the South American coast. A submarine so well-preserved that it shouldn’t exist. Eager to learn its secrets, a team of marine archaeologists arrives at a unique seafloor habitat to study the wreck up close. But something has survived in the empty sub. A dark and terrifying presence.

Answering the panicked researcher’s distress call, CUSP sends John Decker to assess the situation. What he finds on the cold and lonely ocean floor is unlike anything he has seen before. A horror from the blackest days of the war. And it doesn’t want them to leave. At least, not alive.

Ghost Canyon: They are found huddled together in a frontier mineshaft - three mummified corpses sitting near a vein of gold so rich it would have made them wealthy. Yet they never tried to leave. Instead, they sat down and starved to death rather than walk out.

When Robyn Miller inherits her father's share of an old ghost town in Nevada that has been in the family for generations, she decides to pack up and make a new life by creating a one-of-a-kind wedding venue and tourist attraction. Eager to put her plans into action, she hires a trio of geologists to survey the crumbling gold mine so that she can start offering tours. But only one of them makes it out alive, and he brings with him a tale of mummified corpses and seams of gold. He also tells of a creature deep in the tunnels. A beast with glowing red eyes that attacked them, killing his companions and almost murdering him.

The local police, unable to find answers, call in the FBI, who in turn ask CUSP for help. When John Decker arrives in the remote mining town, he finds a terrifying adversary that dates all the way back to the Gold Rush, and an ancient legend come to life.

Cryptid Quest: In the dense and dangerous Amazon, the crew of the supernatural reality series, Cryptid Quest, makes a stunning discovery: a Bronze Age fortress of Mayan design, hidden by impenetrable jungle and far from where it should be. But that’s not all. They also find tantalizing evidence of Egyptian and Greek influence - an impossible collision of ancient cultures that leaves them baffled. Then, without warning, they disappear without a trace.

Determined to find out what happened, John Decker travels to South America. Arriving in the humid Amazonian jungle, he joins a team of specialists pulled together from all corners of the globe, including a ghost from his past - an old flame he thought was out of his life forever.

But this is the least of Decker’s worries, because when the group treks deep into the overgrown and unexplored jungle, they find themselves trapped in a forgotten land where death lurks around every corner, and the nightmares of the ancient world live on. Cut off from civilization and under siege, they must solve the riddle of the ancient ruins and find a way out, or die trying....