Two years after the tragic death of Clara Thompson, those involved have been put to trial for freeing the creature into the ocean which, although destroyed, birthed young which were never found. When a legal loophole sees the accused go free without charge, a chance encounter for Henry Rainwater with Clara's sister, Jade, pulls Henry back into a world he promised never to return to. Jade's independent investigations into the death of her sister have led her to billionaire Charles Decker, a man who she claims not only has live specimens of the creatures, but is actively breeding them. Along with Ross Mackay, Henry and Jade begin to investigate Decker who, when challenged, seems more than willing to share the information about his work, further rousing their suspicions. When the trio are invited by Decker to the Triton Spire - a self-contained laboratory housed a mile beneath the Pacific Ocean where he is breeding the creatures - the trio discover that Decker is not being entirely open with them in relation to his intentions, and in fact has a very specific purpose in mind for pushing on with his breeding programme. Under threat from one of the worst tropical storms on record which is due to hit the facility and potentially halt their investigation, Henry and Jade continue to search for the truth, unaware that both human and animal demons from Henrys past are about to come back to haunt him. As the final part of the From the Deep trilogy is played out in the pressurised, claustrophobic confines of the Triton Spire, lives will be irreversibly changed as the desperate, distressed calls of Decker's captive creatures draw in their fully grown, wild brethren, and sets in motion a chain of events which will change the lives of everyone in the facility forever...