 | |
| Series | Sonic Underground (DiC, 1999) |
| Season | Season 1 (the only season) |
| Episode | Episode 15 of 40 (production order) · production no. 415 · WildBrain no. 115 |
| French title | Tonisonic |
| First aired (France) | 24 February 1999 · TF1 |
| First aired (US) | 17 September 1999 · BKN Kids II (syndication) · 15th in US broadcast order |
| Written by | Mark Edens |
| Directed by | Marc Boreal, François Hemmen and Daniel Sarriet; Tom Smith (US) |
| Song | “The Fastest Thing Alive” (also listed as “I Wish I Could Go Faster”) |
| Previous episode | Bug! (S01E14) |
| Next episode | Friend or Foe? (S01E16) |
Sonic TonicThe Hanging GardensSibling rivalry
Sonic Tonic is episode 15 of Sonic Underground, DiC’s 1999 cartoon about Sonic, Sonia and Manic, the hedgehog triplets of Queen Aleena. It is number 15 in production order – the order TF1 first showed the series in France, where it premiered on 24 February 1999 – and it was the 15th episode to air in the United States, on 17 September 1999. It was written by Mark Edens, and its song is “The Fastest Thing Alive” (also listed as “I Wish I Could Go Faster”).
Synopsis
Robotnik’s tree-cutters invade the Hanging Gardens, a refuge Queen Aleena created for her children, looking for the fabled Velocitree, the fastest-growing plant on Mobius. Distilled in his mobile lab, its essence becomes Sonic Tonic, a yellow brew that gives anyone Sonic’s speed, as Dingo and then Sleet find out.
Sonic forbids his siblings to touch the stuff, which goes down badly: behind his back, Sonia and Manic grumble that being the fastest does not make him the leader. Sonic is captured in Robotropolis, but then the tonic’s side effects kick in. Sleet and Dingo’s feet swell until they burst out of their shoes, and Sonic escapes with the potion.
When the van gets a flat and Sonic leaves them to change it, Sonia and Manic drink some tonic and suffer the same giant-foot fate. Sonic sorts things out and pours the tonic over the gardens, which spring back to life and tie the villains up in greenery. On the road home the siblings apologise to each other, and laugh at how slowly they are suddenly going.
The Song: “The Fastest Thing Alive” (also listed as “I Wish I Could Go Faster”)
“The Fastest Thing Alive” celebrates Sonic’s speed in an episode about everyone else wanting it. Sonic Wiki Zone also lists it as “I Wish I Could Go Faster”.
Key Moments
- The Velocitree is turned into Sonic Tonic.
- Sonia and Manic resent Sonic acting as leader.
- The tonic’s side effect is enormous feet.
Trivia
- The French title, Tonisonic, simply turns the potion’s name around.
- Written by Mark Edens, who wrote or co-wrote eight of the 40 episodes.
- Each character leaves a different coloured streak when the tonic kicks in.
Watch the Episode
The full episode, uploaded by WildBrain’s official Sonic The Hedgehog – WildBrain YouTube channel (checked 6 November 2026).
Part of our Sonic Underground episode guide. The series page covers the characters, the songs, the prophecy and the show’s history.
Sources: titles, writers, songs and air dates from Luke’s original Sonic Scene guide, cross-checked with Wikipedia, Sonic Wiki Zone and Sonic Retro (Wayback copy); synopsis written for Sonic Scene from the episode, its official description and several fan references; title card and screenshots via Sonic Wiki Zone, copied to our media library.