Centuries after Twilight Sparkle's adventures with her friends, a young mare named Featherwisp finds herself in over her head when she and her friends travel to Kelpie Cove to try and reason with the merponies who have been sinking Equestrian supply ships. Now, they must escape the Cove and find some way to stop the coming war between ponyfolk and merfolk. Featherwisp is certain that the only way to stop her mother and the Queen of the kelpies from declaring war is to use the Elements of Harmony, mysterious objects of untameable power that she read about in books. The only problem is that the Elements have been missing for hundreds of years. Is there any other way to stop the war before lives are lost?