The Two Brothers,Mario and Luigi have started Super Mario Bros. Plumbing. After a strange leak going on,Mario and Luigi went to check it out. They notice a green pipe and they get accidentally sucked in. They ended up In Mushroom Kingdom where they were taken to the Castle by the Guards. There,They met Princess Peach. Then,A Guard came in to warn her that Bowser is approaching.

Bowser and his Armies attack the castle and kidnaps the Princess. Toad begun training Mario and Luigi to get power by taking any Mushrooms and Flowers. They begin their journey.

Meanwhile at Bowser's Castle,He convince Peach to marry him so they could rule the Kingdom,which Peach is disgusted due to his Evil Nature. Bowser learned that Mario and Luigi are coming this,so he sent Tryclyde to kill them.

Mario and Luigi are confronted by Tryclyde. Mario uses Fire Flower to transform. He fires the Fireball at the Rocks,causing a landslide to crush Tryclyde to death,but Luigi gets knocked unconscious. Mario entered Bowser's Castle to confront him. He saves Peach and escape. Bowser rode his Clown Car to pursue them. Mario and Luigi fights with Bowser. They uses two cape feather to transform. They damage the Clown Car and Peach stuffed Bowser's mouth with a Poison Mushroom,causing him to shrink and Toad throws him into the sea.

Mario and Luigi are hailed as Heroes. They celebrate their Spaghetti dinner with Peach and Toad.