Third and final sequel to "The Little Scottish Mermaid." Two months after Medusa's defeat, she escapes her ice prison and with her goons, seeks revenge against Merida and her family and friends even more by discovering Atlantis' elemental power source, the Book of Elements. And when Medusa steals the book with Ahkmunrah's evil brother, Kahmunrah's, help, it's up to Merida and her family and friends, both land and sea-wise, to journey to Atlantis within the Bermuda Triangle, and with the help of the Pure Elementals, save the ill Fergus and Elinor, Atlantis, and the world from the wrath of the evil Elemental Masks and Titans.
Original cast from the first two stories, except Sedusa, Vanitas, and Braig, returns.
New cast
Returning villains: Medusa, Brutus, Nero (The Rescuers), and Metalseadramon (Digimon)
Evil King of Atlantis: Kahmunrah (Night at the Museum: Battle of the Smithsonian)
Good King of Atlantis: Ahkmunrah (Night at the Museum Trilogy)
Queen of Atlantis: Shahiras (OC character)
Pure Elementals: Groudon, Kyogre, Rayquaza, and Ampharos (Pokemon; Their powerful forms are their Primal and Mega forms respectively)
Evil Elemental Masks: Rok-Ko, Wa-Wa, Py-Ro, and Lo-Lo (Crash Bandicoot)
Evil Elemental Titans: Rock Titan, Ice Titan, Lava Titan, and Tornado Titan (Hercules)
Guardian of Atlantis and the Bermuda Triangle our heroes befriend from Angie's sob story: Tamatoa (Moana)
Musical numbers
1 Swim This Way (From "Kingdom Hearts 2") (When Merida and her family and friends celebrate Merida and Ralph's 12th wedding anniversary)
2 I Didn't Know That I Could Feel This Way (From "Lady and the Tramp 2: Scamp's Adventure") (When Angie and Mikey are having their first date on land with their friends and families' help)
3 Merida's Lullaby (Parody of "Grandma's Lullaby" from "The Land Before Time 4") (When Merida comforts Angie while coping with Fergus and Elinor falling mysteriously ill)
4 No Fear (From "The Swan Princess") (When Merida and her friends and family agree to go to Atlantis to save Fergus, Elinor, Atlantis, and the world)
5 Shiny (From "Moana") (When Tamatoa tried to prevent Merida and her friends and family from entering the Bermuda Triangle, unaware of the truth that they're the good guys, not bad guys)
6 It Takes All Sorts (From "The Land Before Time 4") (When Merida and her friends and family befriend the Pure Elementals along with Ahkmunrah and Shahiras, learning they're on the same quest on saving their loved ones, Atlantis, and the world)
7 You're Only Second Rate (From "Aladdin 2: The Return of Jafar") (When Medusa and Kahmunrah imprisons Ahkmunrah and Shahiras)
8 Shall We Dance (From "The King and I (1999)") (In the very end when Merida and her family and friends, after they save Fergus and Elinor, Atlantis, and the world, celebrate their victory on land and sea)
Chapters
Chapter 1: Opening/Swim This Way
Chapter 2: Medusa and her Goons' Revenge Seeking/Meeting Kahmunrah
Chapter 3: Lessons of Atlantis/Angie and Mikey's First Date
Chapter 4: The Book of Elements Stolen/Chaos Befalls the World
Chapter 5: Fergus and Elinor Fall With a Mysterious Illness/Merida Comforts Angie
Chapter 6: Discovering the Cure/Going to the Bermuda Triangle
Chapter 7: Meeting Tamatoa/Angie's Sob Story
Chapter 8: Finally at Atlantis/Befriending Ahkmunrah, Shahiras, and the Pure Elementals
Chapter 9: Medusa, Kahmunrah, and their Goons Take Control/The Evil Elemental Masks and Titans Awaken
Chapter 10: Getting the Book Back and Final Battle/Restoring Atlantis and the World
Chapter 11: Saving Fergus and Elinor/Ending
For original story: The Little Scottish Mermaid
For sequel: The Little Scottish Mermaid 2: Return to the Sea