While Timon chases a beetle, he slips on a marble. When he wonders what the marble is doing in the jungle, he finds Pumbaa looking for it, unaware that Timon is holding it. Pumbaa tells his friend that it's not an ordinary marble, it is a lucky marble. Timon doesn't believe in the marble's powers until the beetle flies inside his mouth. The meerkat then hides the marble in his armpit.
Later, Timon still doesn't believe that the marble is lucky until he finds a dollar lying on the ground. When he picks up the dollar, the marble falls out of his armpit and Pumbaa praises his friend for finding it. Timon throws the marble and it lands on Pumbaa's tummy. Then a tiger shows up and is about to eat Timon. Pumbaa tricks the tiger to make it eat him instead. The tiger throws Timon to a tree, causing the tree to break and fall on the predator. Timon now steals the marble from Pumbaa.
Timon finds a big gold rock somewhere in the jungle while Pumbaa falls in a snake pit. As Timon tries to make the snakes let go of Pumbaa, the marble falls out of his armpit and Pumbaa takes the marble, which now makes the snakes go on Timon.
Later, a mailman shows up and gives Pumbaa a letter that says that he won two tickets to Monte Carlo. When Timon and Pumbaa are about to get on the plane, Timon takes Pumbaa's marble and puts it in his armpit again. The flight attendant makes Timon sit on one of the airplane seats and has Pumbaa tied up on one of the wings. When Timon gets out of the plane, the marble falls out of his armpit and Pumbaa takes it and puts it in his tummy.
Timon and Pumbaa arrive at a casino at Monte Carlo. The two play games in there and Pumbaa is the one winning all the money. When the two friends get back home with Pumbaa having a bag of money, Timon flips the warthog and snatches the lucky marble. The flight attendant shows up and gives Timon a bag of money.
Timon and Pumbaa start fighting over the lucky marble. The marble then falls in the river and Pumbaa goes after it. Timon tries to stop his friend from diving into the water, but the warthog insists on doing so in order to retrieve his marble. When Pumbaa jumps, Timon makes him realize that the river is heading towards a waterfall. The meerkat then jumps to try to save his friend. Timon and Pumbaa fall down the waterfall, but survive and it is revealed that it is due to Timon catching the marble.
Timon apologizes to Pumbaa for stealing his marble and gives it back to him. Pumbaa opens a "hole" in his tummy for Timon to put the marble in so it can be safe, but it turns out that there is another lucky marble inside, making the duo realize that the marble probably had nothing to do with the good and bad luck that has happened to them. Pumbaa then tells Timon that the luckiest thing that has ever happened to him was when he met the meerkat, which was before he had his lucky marble.