Marvin and his school friends are tending to the school garden when supervillain Violet Vine appears and uses her powers to make the plants grow out of control. Before long, the garden and school are covered in snaking vines, and kid-eating Venus flytraps! It's time for Marvin to swap his gardening gloves for his superhero suit and become Marv - unstoppable, invincible, and totally MARVellous! Only then can Marv get the garden, and Violet Vine, under control.