Genesis. The Dogs of War, #0.5

After a harrowing mission, Navy SEAL Aiden Willingham was approached to participate in a secret research project. Now he realizes the Spartan Project is a covert, multinational government testing program run by a private company called The Silverstone Collaborative. The company's mission is to create super soldiers, men capable of recovering from horrendous illness and injuries, using a serum derived from indigenous plants in the Amazon rainforest.
The program is brutal and when the men object, they go from test subjects to caged prisoners overnight. The doctor leading the program is world-renowned for his cutting-edge cures, but Aiden sees only the madness in his eyes. The serum is producing results, but men are dying every day of testing. And, as more men die, the experiments turn more deadly. What the research team doesn't realize is exactly what the serum is doing .
creating a psychic connection between four of the men. Aiden and his team have to break out of the camp before they're compromised further. But getting out of the camp is the easy part. They know that actually living to bring the company to justice is going to be the most difficult mission any of them have ever undertaken.