One of Bruce Wayne's oldest friends is found dead in Gotham Bay, ripped apart by a mysterious sea monster. As he investigates the bizarre death, Batman is drawn into a fatal encounter with the murderous creature.
Bruce Wayne hosts the Museums Annual Fundraiser costume party on one of his yachts. He is a little put out due to the fact that Edward Nigma, the Riddler, was invited in order to add to the excitement.
One of Bruce's childhood friends, Matthew Atkins, is also attending. Matthew has a tendency to indulge himself too much. He steps out to get some air when it is discovered that he's fallen overboard.
Bruce jumps in without anyone seeing him. Sharks have started their attack on Matthew. From a hidden hull in the yacht, Bruce is able to launch a Bat-sub to help deal with the sharks and to bring Matthew on board. Bruce is unable to save Matthew but discovers some sort of shark tooth in his hand.
Sensing that there was more to his death, Batman is on the case. Matthew had pretty much spent his entire inheritance yet was still spending money at a great rate. Batman also finds the shark bites on his body peculiar. The tooth he was able to recover was not from a common breed.
Batman searches his apartment and is lead to the museum. It seemed that Matthew, with the help of his "girlfriend" the museum dirctor, was switching rare archaeological pieces with fakes and selling them on the black market.
Hearing a muffled scream, Batman investigates. He finds the Riddler unconscious on the floor and is attacked by a Kiribati warrior. The warrior seemingly begins to get the upper hand when the Riddler awakes. He shoots the warrior in the back with a flaming arrow and Batman is able to tie him up. From the shadows a gun is pointed at them when Batman takes them out too. It turns out to be the museum director.
The warrior was the museum's restorer. They, along with Matthew were all in on the scheme to sell the artifacts. When Matthew wanted a bigger cut, they killed him and made it look like an accident.
Batman allows the Riddler to take all the credit as he leaves.