Sea monsters are sinking ships up and down the Atlantic Coast. Enraged that his navy is helpless against this onslaught and facing a possible World War as a result, President Ulysses S. Grant is forced to ask for assistance from the notorious Captain Nemo, in Federal prison for war crimes and scheduled for execution. Grant returns Nemo's submarine, the infamous Victorian Steampunk marvel Nautilus, and promises a full Presidential pardon if Nemo hunts down and destroys the source of the attacks. Accompanied by the beautiful niece of Grant's chief advisor, Nemo sets off under the sea in search of answers. Unfortunately, the enemy may be closerthan they realise...