 Japanese title card · “The Last Chaos Emerald” | |
| Series | Sonic X (ソニックX), TMS Entertainment |
| Season | Season 1 (2003–2004) |
| Episode | Season 1, episode 25 · no. 25 of 78 |
| English title | “A Dastardly Deed” (4Kids) |
| Japanese title | 最後のカオスエメラルド (Saigo no Kaosu Emerarudo, “The Last Chaos Emerald”) |
| First aired (Japan) | 21 September 2003 · TV Tokyo |
| First aired (US) | 20 March 2004 · Fox Box (Fox) |
| Directed by | Yukio Okazaki |
| Written by | Hiro Masaki |
| Storyboard | Toshihiko Masuda |
| Previous episode | How to Catch a Hedgehog (S01E24) |
| Next episode | Countdown to Chaos (S01E26) |
Season finale, part 1Betrayal
A Dastardly Deed is episode 25 of Season 1 of Sonic X and the 25th of the anime’s 78 episodes. In Japan it is called “The Last Chaos Emerald” (最後のカオスエメラルド). It premiered on TV Tokyo on 21 September 2003, and the 4Kids English version followed on Fox Box (Fox) on 20 March 2004. It was directed by Yukio Okazaki and written by Hiro Masaki.
Synopsis
Six Chaos Emeralds have been found – four with Sonic’s group, one each with Knuckles and Eggman – and as the hunt for the last one goes on, Chris is miserable. He wants his friends to get home, but he will miss them terribly; even Mr. Stewart notices, and tells him that letting them go is right. Eggman, meanwhile, sends out E-77 Lucky, a clumsy robot meant to find the seventh gem by sheer luck.
Knuckles, desperate to get back to the Master Emerald, decides the only way home is to bring all the gems together, even if that means a truce with Eggman. He brings Chris into the deal, and Chris quietly takes the group’s four Emeralds without telling Sonic. The two hand them over at the Egg Fort II, hidden in Forest Hill.
Lucky, meanwhile, has tumbled into a rubbish dump – and found the seventh, white Chaos Emerald. The moment Eggman hears, he drops Knuckles through a trapdoor and takes Chris prisoner: he doesn’t care which world he rules, as long as he gets his Eggman Empire. Sonic arrives to see the Egg Fort II lifting off and gives chase.
Key Moments
- Knuckles strikes a deal with Eggman.
- Chris gives Sonic’s four Emeralds to Eggman behind his back.
- The seventh, white Chaos Emerald is found.
Trivia
- Ends on a cliffhanger that leads straight into the Season 1 finale.
- On home video: Japanese DVD/VHS volume 6 (Victor Entertainment, 17 December 2003); 4Kids/FUNimation volume 6, Countdown to Chaos (12 April 2005); the Chaos Emerald Chaos DVD set (2008); and Discotek’s Sonic X Collection 1 (2016) and complete-series Blu-rays.
Watch the Episode
The full 4Kids English episode, uploaded by TMS Entertainment’s official “Anime! on TMS” YouTube channel (checked 6 November 2026).
Part of our Sonic X Season 1 guide. See the Sonic X series page for the cast, theme songs and home video.
Sources: titles, credits and air dates from Wikipedia’s list of Sonic X episodes and Sonic Wiki Zone, cross-checked with each other and with Luke’s original Sonic Scene episode table; synopsis written for Sonic Scene from the episode, Wikipedia’s summary and Sonic Wiki Zone’s plot notes; title card and screenshots via Sonic Wiki Zone, copied to our media library.