Devin and Granny embark on a fantastical undersea adventure. Along the way, they encounter a host of musical aquatic creatures: Ink, an octopus who plays a mean set of drums; his puffer-fish buddy Spike, who sings bass; Missy Turtle and her school of singing Minnows; a rambunctious baby the sea otter named Ottie; a prima donna Starfish named Stella, and many others. Along the way, Devin, Granny and their new friends help Weeber the Penguin find his way back to the South Pole, and together, they clean up the man-made pollution that made Ottie sick.