Jonas Taylor, paleontologist and deep sea diver is once again thrust into a new nightmare as a captured Megalodon known as Angel escapes the aquarium he works at and begins a new reign of terror. Jonas Taylor, paleontologist and former diver knows what horrors lie deep within the Mariana Trench. He continues to have nightmares about his encounter with the megalodon, an ancient shark that was thought to be extinct and murdered his wife as well as several others close to him. Now four years later, Jonas works for his good friend Tanaka at his institute, along with his new wife Terry Tanaka whom he met through his friend. Together they have continued to study the offspring of the megalodon they killed, a stunning female named Angel who has grown to be much larger than her mother.
Things are not going well for the institute which has come under new ownership by a man named Benedict Singer. Benedict hopes to profit off of Angel, and open the aquarium to the public against Tanaka and Jonas's wishes. They know that Angel is unpredictable and tourist activity could set her off on a rampage. Unfortunately, Benedict will never see his dream as a reality.
Late one night, three young boys sneak into the institute with the hopes of catching a glimpse of the prehistoric shark. While in the underwater observation deck, the teens torment and aggravate angel who bursts through the viewing glass. The teens struggle to swim for their lives, but Angel attacks and kills one while the other two drown after becoming cornered in the underwater area.
The commotion from the attack alerts Jonas that something is wrong. He radios his good friend Mac who also works on the institute's grounds and together they go to investigate. When they find the carnage, Jonas and Mac jump into the tank in order to survey the damage. While submerged they are attacked by a flurry of male great white sharks who have become attracted to Angel because she is ready to mate. Mac notices that Angel's tank is badly damaged yet too late as Angel rams the gates to her tank and breaks free.
Mac quickly grabs a nearby tagging gun and is able to shoot a tag into Angel before she disappears. Realizing Jonas is badly injured, Mac pulls him from the tank and rushes him to the hospital with his wife Terry. In the days following her escape, Tanaka has grown increasingly weary. Afraid for the worst, and another massacre in the future. Tanaka realizes they must recapture her as soon as possible. Jonas knows she will head back to the trench by instinct, but knows that now that she has tasted human blood, she will also seek that out as her new food source.
Over the next week, Angel sightings crop up as she destroys a ship, kills surfers and even kills a whale named Tootie that was released back into the wild by Sea World. As the body count continues to climb, Jonas teams up with a scientist named Michael Maren, whose ego is bigger than his career. Unknown to Jonas, Michael is working with Benedict's assistant Celeste who is determined to find the Mariana Trench before them. Celeste tries to coerce Jonas into revealing the location of the Trench, but Jonas refuses, knowing that if Angel were to get into the hands of Benedict it would be a disaster. Jonas, Michael and Tanaka attempt to capture Angel but fail due to her size and speed. After tracking her path and predicted trajectory, Jonas concludes she is heading at full speed to the trench.
Back on the mainland, Benedict Singer pursues Jonas's wife Terry and asks her to assist him on his deep sea research station under the impression that she is studying sonar records to determine what happened to one of the station's research vessels. While there, Terry realizes the station has uncovered a new marine predator thought to be extinct known as the Kronosaur. While it was said this species was a solitary hunter, due to being trapped in the trench, the species had evolved to hunt in pacts. Terry realizes the operation is dangerous and is almost killed by the station's crew but is able to escape in a lifeboat submarine while the crew is torn apart by the raging Kronosaurs.
Meanwhile, still in his pursuit of Angel, Jonas receives word of his wife Terry being caught up in the secret operation the deep sea research station. Determined to save her as well as end this obsession with megalodons once and for all, Jonas heads to the research station to confront Benedict and Celeste who fled days prior after discovering the trench's location. After boarding the station, Jonas is shocked at the Kronosaur discovery, realizing that there could be many more extinct marine life living in the trench.
Confronting Benedict, it comes to light that he had discovered a gas within the rocks of the trench that could be used in fusion and make him more money than ever. Their digging uncovered the Kronosaurs that were living deep in the trenches. The station is attacked by the Kronosaurs as Angel arrives in the trench. Benedict is killed by one of the Kronosaurs and Celeste escapes in a submersible. However, Angel has other plans for her and destroys the sub and devours Celeste.
Jonas reunites with his wife Terry who returned to the station after her escape, and together they head to the surface. On their way, they are attacked by another Kronosaur, but Angel attacks the beast allowing Jonas and Terry to escape. As they reach the surface, Terry and Jonas watch in awe and in horror as Angel gives birth to two babies, the new family disappearing deep into the trenches.
Jonas knows the future looks grim as more megalodons are introduced in the ecosystem, they could have real environmental disaster. Terry assures him this is a new dawn for science, but Jonas expresses his hope to have a normal life away from the horrors of the deep.
Best part of story, including ending:
I loved the new species of prehistoric marine life introduced and how they added to the suspense and terror of the story. Knowing the trench holds more animals that survived really brings an interest to what could be explored in further sequels.
Best scene in story:
I loved the scene where Celeste is killed by the kronosaur during her escape. Jonas knows she is a threat to them and is able to entice Angel into attacking her. The moment was wicked and cruel yet the ultimate justice.
Opinion about the main character:
Jonas is determined to do the right thing no matter what the cost. He realizes his passion for this creature has unleashed a force so powerful it could destroy the earth's ecosystem. He wants to right his wrongs yet tends to find more death and destruction the harder he tries to fix things.