A young woman named Song is abducted into the Triple Threat Triad, and must adapt to life as a professional criminal as she sinks deeper and deeper into Republic City's world of organized crime.

While attempting to suck all worlds in existence into Subspace, the evil Tabuu creates a rift that sends heroes Mario, Link, Samus, Kirby, Fox, Sonic, Snake, and Pit into the same world. Now the eight of them are the team known as the Smash Bros. and they are determined to protect this world from evil until they can find a way to get back to their own worlds.