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| Series | Sonic Underground (DiC, 1999) |
| Season | Season 1 (the only season) |
| Episode | Episode 36 of 40 (production order) · production no. 436 · WildBrain no. 136 |
| French title | Agent inhibeur |
| First aired (France) | 9 May 1999 · TF1 |
| First aired (US) | 18 October 1999 · BKN Kids II (syndication) · 36th in US broadcast order |
| Written by | Ben Hurst and Pat Allee |
| Directed by | Marc Boreal, François Hemmen and Daniel Sarriet; Tom Smith (US) |
| Song | “Have It All Again” |
| Previous episode | The Big Melt (S01E35) |
| Next episode | Bartleby the Prisoner (S01E37) |
CyrusSleeper dartsThe Badlands mine
Sleepers is episode 36 of Sonic Underground, DiC’s 1999 cartoon about Sonic, Sonia and Manic, the hedgehog triplets of Queen Aleena. It is number 36 in production order – the order TF1 first showed the series in France, where it premiered on 9 May 1999 – and it was the 36th episode to air in the United States, on 18 October 1999. It was written by Ben Hurst and Pat Allee, and its song is “Have It All Again”.
Synopsis
On a mission in a distant sector, the siblings learn that Freedom Fighters have been disappearing. Sonic races to help but is too late: a group of them, including Cyrus’s father, have already been roboticized after being knocked out by Robotnik’s newest weapon, the Sleeper.
The Sleeper darts put victims to sleep so they can be collected at leisure, and when Manic is hit, the hunt for their source becomes personal. With Cyrus at their side, the hedgehogs trace the darts’ fuel to a mine in the Badlands.
Sonia’s spinning tornado flings a supply ship across the sky, Sonic snatches a nugget of the precious ore from Sleet and tosses it up for Sonia to blast, and Manic’s drums split the ground open, destroying the mine as Robotnik’s ship blasts off.
The Song: “Have It All Again”
“Have It All Again” looks forward to the day the Resistance gets back everything Robotnik has taken, a hope with an edge for Cyrus, whose father has just been roboticized.
Key Moments
- Cyrus’s father is roboticized.
- Manic is hit by a Sleeper dart.
- The siblings destroy the mine that fuels the darts.
Trivia
- Cyrus’s father was the reason Cyrus first worked for Robotnik, in Tangled Webs.
- The French title, Agent inhibeur, puns on agent inhibiteur (an inhibiting agent).
- Aired 18 October 1999 in the US, in the series’ final week.
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.