1Beginnings (Origins: Part 1)
The history of the Underground is told in detail, from the fall of Mobotropolis to the rise of Robotnik.
2Getting to Know You (Origins: Part 2)
The Hedgehogs begin to learn the important lessons of what it takes to be a freedom fighter.
3Harmony or Something (Origins: Part 3)
Manic, Sonic and Sonia must end their training early when Robotnik threatens the Oracle and takes a member of the resistance hostage.
4To Catch a Queen
Argus, a captain of the Queen's guard, is captured by Sleet and Dingo before he can reach the secret rendezvous where he was to meet Queen Aleena.
5Mobodoon
Sonic, Sonia and Manic return to their birthplace, Mobodoon, a beautiful, festive town.
6The Price of Freedom
Sonia travels to east Mobius to visit her friend Mindy at the LaTour estate.
7Underground Masquerade
Sleet and Dingo plan to collect the taxes owed to Robotnik from the Duke of Velcronia but keep it for themselves.
8Tangled Webs
The sinister Robotnik blackmails Cyrus, an old friend of Sonic's, by holding his father hostage.
9The Deepest Fear
On a trip to Port Mobius, Sonic, Manic and Sonia are told that ships are sinking due to the Mobian sea-beast.
10Who Do You Think You Are?
Queen Aleena's royal journals are rumored to be buried under a palace in the city of Tashistan.
11The Last Resort
While lost in the wastelands of Mobius, Sonic, Manic and Sonia stumble upon an oasis called Lake Valley Resort.
12Come Out Wherever You Are
Sonia is invited to a debutante ball, but before she can be officially announced to society, she and her brothers, Manic and Sonic, have an important mission.
13Winner Fakes All
Robotnik organizes a track meet to lure Sonic into a trap.
14A Hedgehog's Home is Her Castle
The Hedgehogs receive a message they believe is from their cousin.
15Artifact
The Hedgehogs steal historical artifacts of Mobuis from Robotnik before he can pawn them off at an auction.
16Bug!
A faction of the Freedom Fighters is wiped out by a swarm of metallic fly-bots.
17Sonic Tonic
A speed enhancing fluid deemed Sonic Tonic is created by Robotnik to make him as fast as Sonic so that he may finally catch him.
18Friend or Foe
The Hedgehogs converge on the Floating Island, in their latest attempt to find their Mother.
19Head Games
As Sonic begins to chow chili dogs for a snack, he finds a message in the sack from his mother urging him to head to Speedster Island.
20When in Rome
Sonic becomes frustrated that maybe all of their efforts of fighting for freedom seem futile.
21The Jewel in the Crown
Robotnik has his sights set upon Queen Aleena's crown jewel, which glows as it is moved closer her.
22Three Hedgehogs and a Baby
Sonic, Manic and Sonia find an abandoned baby in an alley and begin a search for the baby's parents. Manic grows particularly fond of the child and decides that instead of taking the baby to a shelter as Sonic and Sonia ordered, the baby would be more comfortable at the Underground sanctuary. While Sonia and Sonic are working to uncover another plot of Robotnik they find that the baby is not a baby at all, but an android equipped with cameras to spy on the Underground. Sonia and Sonic frantically search for their brother before he, unknowingly, exposes the location of the secret sanctuary.
23Dunes Day
Sonic and his siblings travel to the outskirts of Mobius to recruit a tribe of nomads for the Resistance.
24Mummy Dearest
Sonic, Manic and Sonia invade Robotnik's lair to retrieve the Hedgehog crest.
25The Hedgehog in the Iron Mask
The Hedgehogs latest quest to find their mother takes them to the prison tower where they encounter a masked stranger who insists he is family.
26Six Is a Crowd
The Oracle advises the Hedgehogs to undertake a mission which could reveal answers about their future.
27Flying Fortress: Chaos Emerald Crisis Part 1
What is supposed to be a vacation for Sonic, Manic and Sonia turns into a battle to save Mobius when Robotnik attacks with his newest weapon - the Flying Fortress.
28No Hedgehog Is an Island: Chaos Emerald Crisis Part 2
Sleet and Dingo escape the Flying Fortress with the Chaos Emerald.
29New Echidna in Town: Chaos Emerald Crisis Part 3
Knuckles reluctantly makes a deal with Robotnik to turn over Sonic and his family in exchange for finding the Chaos Emerald that will save Mobius.
30Wedding Bell Blues
Robotnik announces that he will marry Queen Aleena in a plot to become the king of Mobius.
31Country Crisis
Queen Aleena advises the Hedgehogs to travel to a valley of Mobius so that they can bring about peace between two contingents of the resistance that have split.
32Haircraft in Space
Robotnik is using the local hairdresser, Doo-bot, to get information on the citizens that are against him.
33Healer
A self proclaimed scientist has come to Robotropolis with a device that will reverse the effects of Robotnik's robotisizer.
34Sonia's Choice
Robotnik has arranged a museum exhibit of the Royal family goblets.
35The Big Melt
The Hedgehogs vacation is interrupted by the news of Robotnik's latest weapon.
36Sleepers
On a mission in a distant sector of Robotropolis, the Hedgehogs are informed that freedom fighters have disappeared and are going to be robotisized.
37Bartleby the Prisoner
Robotnik captures Bartleby and uses him as bait to capture Sonia.
38Art of Destruction
Robotnik's new weapon, Art, is the enforcer of Robotropolis new eradication policy.
39The Pendant
The newly discovered Emerald Peninsula is a perfect place for Robotnik to add slaves to his empire.
40Virtual Danger
Sonic and Manic play a game of virtual reality to enhance their pilot skills.