The coastal town of Bristol Cove is known for its legend of once being home to mermaids. When the arrival of a mysterious girl proves this folklore all too true, the battle between man and sea takes a very vicious turn as these predatory beings return to reclaim their right to the ocean.

Max is assigned to the White House while Butch, the secret service dog, is on maternity leave. He meets TJ, a 12 year old boy, who is the President's son. Due to his father's high profile, he is trying hard to fit in and lead a normal life. During a state visit by the Russian President and his daughter, Alexandra (Alex), TJ is asked to accompany her, during their stay. TJ befriends Alex, but when they get into trouble, Max comes to the rescue!