New Super Mario Bros. Wii

New Super Mario Bros. Wii was the kidnapping of Princess Peach during her birthday.

History
Today is Princess Peach's birthday. On that day, she was showered with many gifts and fireworks, and even a massive birthday cake. The birthday cake, however, was quickly revealed to hold the Koopalings. Digging Peach inside the cake, they fled the castle via airship. Mario, Luigi, Yellow Toad and Blue Toad, at first dazed from the attack, immediately ran after the airship.

The Toads inside the castle, wanting to help the group, shot out an abundance of Propellor Mushrooms and Penguin Suits to aid the Mario Bros. and Toads in their quest.

Throughout their road through the 8 worlds, they are impeded by each member of the Koopalings or Bowser Jr. inside the airship. In World 8, Kamek would even fight the group.

Arriving at Bowser's Castle, the group believed they had saved Peach by dropping down Bowser, but it was Kamek in disguise. He showers down some magic on Bowser, which grows him to an enormous size. Wading their way through the progressively destroyed infrastructure, they find the real Princess Peach and a massive switch underneath her.

Pressing the switch, the floor under Bowser gives out, sending him tumbling down. Peach safely floats down from her cage and is finally freed. While Mario escorts Peach out of the castle, Luigi, Yellow Toad, and Blue Toad find an air balloon for them to fly back to Peach's Castle. On the way back home, Peach tells Mario if he had heard of the secret World 9.

The Koopalings painfully return back to Bowser's Castle to try and flip Bowser back upright. They manage, but then Bowser's Castle crashes down on them.

Timeline

 * Unlike New Super Mario Bros. and New Super Mario Bros. 2, which featured Bowser Jr. and the Koopalings respectively on their own, in this game Bowser Jr. and the Koopalings work together to enact Bowser’s plan, indicating that this game may take place after both of those titles.
 * The Junior Clown Car appears, placing this game after the events of Bowser Jr.’s Journey.
 * This is heavily implied to be the first adventure of Blue Toad and Yellow Toad, placing this game prior to their later appearances.
 * This game features a new design for Peach’s Castle, likely placing this title after previous games featuring the Castle’s appearance from Super Mario 64.
 * Bowser’s Castle from New Super Mario Bros. reappears, and it is destroyed by the end of this game, placing this game after all previous games featuring this castle. This also likely leaves Bowser homeless.
 * Propellor Mushrooms and Penguin Suits are likely spread around the Mushroom Kingdom for the first time in this game.
 * A clip of Peach reading her letter from the intro of Super Mario Galaxy plays during the credits, perhaps indicating that this game takes place directly prior to it.