Super Mario 64 begins with a letter from inviting Mario to come to her castle for a cake she has baked for him. When he arrives, Mario discovers that has invaded the castle and imprisoned the princess and her servants within it using the power of 105 of the castle's 120 Power Stars. Many of the castle's paintings are portals to other realms, in which Bowser's minions keep watch over the stars. Mario searches the castle for these portals to enter the worlds and recover the stars. He gains access to more rooms as he recovers more stars, and will have to tackle three obstacle courses leading to a battle with Bowser. Defeating Bowser the first two times earns Mario a key for opening another level of the castle, while the final battle releases Peach and rolls the credits. Peach rewards Mario by baking the cake that she had promised him.