Riding on the back of Monty, the Whale Express, to the Beachcomber Islands, the mermaids come under attack from a whaling boat. Jess devises an ingenious plan to outwit the whalers as well as helping the smaller sealife at the bottom of the ocean as well. Although Jess puts herself into a lot of danger to save her friends, her actions also lead the brave mermaids towards the next Snow Diamond.