The Not-So-Sinister Sponge was the third short story in the Short Trips anthology Short Trips and Side Steps. It was written by Gareth Roberts and Clayton Hickman. It featured the Fourth Doctor, Romana II and K9 Mark II.
The Doctor, Romana, and K9 arrive on an uninhabited planet made entirely of confectionery. K9 seems in a bad mood, and Romana realises it is K9's birthday. To celebrate the occasion, she takes the Doctor's TARDIS to Barastabon to fetch a dedicated sponge cake from the Masterbakers of Barastabon. After a brief time storm-induced detour to the planet Kendrax during which she ably foils an alliance of the Master, the Daleks and the Cybermen, she returns with the Cake.
K9 is cheered by the gesture, but before the trio cut the Cake, it comes to life and asks politely not to be eaten. The Doctor theorises that the unique combination of a trip in the TARDIS, exposure to the telepathic circuits and the unusual properties of the confectionery planet brought the Cake to life. At K9's suggestion, they release the Cake to live out its life on the confectionery planet.
- The Masterbakers come from the planet Barastabon.
- The Doctor flips through his Five Hundred Year Diary to figure out what he's forgotten. Romana has a time-o-fax.
- After being thrown off course by a time storm, Romana lands on Kendrax and foils a joint plan by the Master, the Daleks and the Cybermen.
- This is the first of four connected stories in this volume featuring the Fourth Doctor and Romana II.
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