All of the Koopalings were playing in the play room when Bowser came in with a little white person.

"Who's that, King Dad?" asked Roy.

"This is Doopliss," answered Bowser. "He will be visiting us for the day."

Bowser left the room. "Good," said Doopliss quietly after Bowser had left. "Now I can kill one of these munchkins."

"I got an idea!" said Larry. "Let's play Lights On, Lights Off. First, we put all of these items on the floor." He put a ball, a pair of glasses, a rod, and a bow on the floor.

"HEY! All of that stuff is ours!" complained Wendy.

"I know. When the lights go out, one of you get your item and replace it with a fake item. Ready..." Larry shut off the lights. "GO!"

Suddenly there was a scream! Larry turned the lights on. Everything was normal, except Doopliss was gone. "Uh oh. King Dad told me Doopliss could transform into anyone," Larry said.

"I knew that jerk was no good," said Iggy.

"So one of us is Doopliss?" asked Ludwig.

"Yup," answered Roy.

"So how do find him?" asked Wendy.

"We do tests," answered Larry. "Ludwig, who's room is this?"

"Morton's," Ludwig answered.

"Wendy, who is our cousin?" asked Larry.

"Susan," answered Wendy.

"Morton, why is your room the play room?" asked Larry.

"Because I have the most toys," Morton answered.

"Lemmy, name another brother I haven't called yet," Larry said.

"Roy," said Lemmy.

"Roy, what's my name?" asked Larry.

"Larry," answered Roy.

"Iggy, walk around these cones without crashing," said Larry. Iggy did as he was told and didn't crash.

"You all passed the tests. Three of you, look for clues!"

The Koopaling who was in Pipe Land looked under the bed. There was a toy car. The Koopaling who was in Water Land checked the items. They were all there, no fakes. The Koopaling who owned a ball looked on the shelf. He found a party hat.

"ENOUGH!" cried Larry. "Doopliss! When I shut the light off, show yourself, then I will turn the light on. If you don't, I'm calling King Dad!"

Larry went to the light and turned it off. There was another scream! Larry turned on the light. Everyone was there, but Doopliss was dead on the floor. "Whoever killed him knew who he was disguised as," said Larry.