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"Baby Kate and the Imaginary Mystery"
Season/Series: 11
Number in season: 5a
Original Airdate: United States June 29, 2007[1]
Canada December 31, 2007[3]
United Kingdom December 13, 2007[2]
Written by: Peter K. Hirsch
Storyboard by: Elie Klimos
Elise Benoit
"Brain's Shocking Secret"
"Strangers on a Train"
Read transcript

"Baby Kate and the Imaginary Mystery" is the first half of the fifth episode in the eleventh season of Arthur.


D.W.'s imaginary friend Nadine goes missing.


Kate announces a Mashed Peas Theater story that will feature Pal, a cat and an imaginary friend.

Baby Kate and the Imaginary Mystery

Kate and Pal are about to bury Mr. Read’s wallet in the garden, when Vicita’s imaginary friend Treenie appears accompanied by Amigo. She asks for help because Nadine has been missing for three days.

Kate and Pal suspect the Tibbles of kidnapping Nadine. Kate remembers how D.W. and Nadine always did everything together.

Pal hides in one of the Tibbles' backpacks and is carried into the Tibble house, where Nemo comes in through the kitchen window and quarrels with Pal. When Mrs. Tibble closes the window, Nemo is trapped. Pal has a fantasy of the twins tickle-torturing Nadine to find out what the initials D.W. stand for. He wants to search upstairs. After being scared by Mrs. Tibble's vacuum cleaner, Nemo agrees to help him. They search the twins' room. Meanwhile, Kate and Treenie wait in D.W. and Kate's room.

The twins come into their room and mistake Nemo for one of Mrs. Tibble's stuffed toys. They put Nemo into the attic where Mrs. Tibble keeps the toys she repaired. Pal follows. While Nemo escapes through an open window, Pal asks Arthur's old teddy bear Stanley and a pink elephant for help. Despite having excellent hearing, the elephant has not heard Nadine, and now Pal is trapped.

At night, Kate tries to get out of her crib and help Pal. Just then, Pal returns after hiding in the Tibbles' trashcan and being taken out by Mrs. Tibble. Nadine returns. She has been on vacation in Fairy Land and forgot to tell Treenie. She mentions that D.W. does not need her so much lately, since she is getting older. Kate offers to have Nadine be her imaginary friend, but assures Pal she will always like him best.





  • Mrs. Tibble's stuffed animals
  • Tooth Fairy (on photograph)
  • Rumpelstiltskin (on photograph)
  • Pixies (on photograph)
  • Snooter


  • In the beginning of the episode, Pal breaks the fourth wall by telling Kate that the viewers do not say anything even when Arthur talks to them.
  • It is revealed in this episode that, as well as being able to speak to non-humanoid animals, babies such as Kate can also talk to toys.

Episode connections[]

Cultural references[]


  • The Xfinity description guide refers to D.W. as a boy in the description: "D.W's imaginary friend Nadine is missing, so his real-life pals set out to find her."[citation needed]

Home video[]



Main article: Baby Kate and the Imaginary Mystery/Gallery