At the start of the series, the Second Earth Recapture Mission from the Mars Base is sent to invade an Inbit-dominated Earth. Hopes are high, the new soldiers are freshly trained, with new weapons and a will to win back the cradle of the human race. Their efforts meet with limited success, and their strike is utterly defeated leaving only a few scattered remnants. One of these remnants is a lone soldier named Stick Bernard, a man who is out for revenge against the Inbit. Armed with only a Ride Armor, a holographic recording of his dead fiance, and a scavenger named Rey he meets along the way, he begins his battle to destroy the Inbit.

Stick and his new partner Rey travel to an island city, entering despite several warnings from the cities ex-inhabitants. They meet a young girl named Mint who leads them to a neighboring island to look for other soldiers. Meanwhile, Stick and Rey's contact within the city conspires with the Inbit to provide their capture. The battle is hard, and it looks as though Stick, Rey, and Mint are done for. From out of nowhere a single red Ride Armor trooper appears and helps them fight off the Inbit Gruab Seconds. The Ride Armor trooper disappears as quickly as she came, and Stick and Rey discover that the people of this "Lost City" conspire with the Inbit in return for peace. Stick and Rey leave disgusted, and Mint joins the battle.

Stick, Rey, and Mint happen upon a frontier town, run-down by the constant wars and apathy. A famous singer is performing at a local club, and the group walks in on a rather heated criticism of her performance. The local riff-raff are restless, and have chosen the famous singing star Yellow to torment. A woman, a customer of the club, intervenes in the dispute, causing the wrath of the thugs to fall upon her. She is able to handle herself, and more importantly, her attackers. Stick notices it was she who rode the red painted Ride Armor and saved their lives in the previous episode. The thugs, dealing with their defeat by Stick, Rey, Mint, Yellow, and Houquet Eroze the Ride Armor rider decide to kidnap a local man. His friend, though he has a sordid past with Mars Base, decides to join forces with Stick's group to rescue his friend. The rescue operation is noticed by the Inbit, and Stick realizes that this deserter, named Jim Austin, has a lot to offer his makeshift team, most notably a well-armed and maintained Legioss Armo-fighter. Jim decides to join Stick's group, as does Houquet and Yellow, who reveals that she is actually a he named Yellow Belmont: a disguise meant to shroud his attacks on the Inbit.

The team is learning to live and fight together. Some people rub others the wrong way, especially Houquet and Rey. While getting supplies, Stick, Houquet, Mint, Rand, and Jim are ambushed by Inbit. Stick realizes that he needs the Legioss to battle this squad, but is afraid to indicate their campsite by making a straight line to the armo-fighter. Yellow Belmont patiently waits by the fighter while the rest of the group fight the Inbit. Rey reveals both his survival skill in the episode, along with his excellent reasoning. He catches fish and helps the group to deal with the horrors of the wild, namely leeches. He also discovers that the Inbit can sense the use of active military hardware. This enables the team to elude the Inbit by using only the minimum amount of energy. With the help of Yellow, Stick finally reaches the fighter and destroys the Inbit patrol that has been tailing them.

Stick's group of makeshift freedom fighters stages a raid on an Inbit HBT cell store to replenish their own supplies. This human-run Inbit reserve is drawn off-guard by a huge concert by the famous Yellow. Stick, Houquet, and Rey infiltrate the storage complex armed with rope and an ancient map of the building and it's secret passages. No plan is ever perfect, and Stick, Houquet and Rey find themselves locked in a sealed room, filling slowly with water. Eventually, they get out, but Yellow has postponed the end of her concert too long, causing the city guard to get nervous. When the robbery is discovered, the Inbit arrive. But with a replenished supply of fuel cells, Stick's group scores an easy victory.

Houquet withdraws from the group more and more, until she finally leaves during the night. Rey follows to see what she is up to. Stick knows that they left, but decides to let them go. Rey follows Houquet to a cavern that surrounds a city. Houquet is at home, through a series of flashbacks and conversations, and remembers why she left and the people that made her leave. Her days in a street gang haunt her, and she confronts the members of a rival gang who beat her severely. This episode is filled with excellent character development for Houquet, and some depth is added to Rey's character at the same time. Stick decides to look for Houquet and Rey, and ends up tangling with the Inbit. Once again, Houquet saves Stick from certain doom, and puts her abusers to shame at the same time. Rey helps Houquet to see her mother one last time, and they are on their way, and she makes a vow to herself to stay with the group of freedom fighters, who have become her family.

Stick's group of fighters continues on their journey to find the Inbit's main hive, making a stop in a small town at Jim's urging. Jim made a promise to a friend he had in his unit, who died in an Inbit attack during the First Earth Recapture Mission. His promise was to deliver a book to his friend's father who lives in this town. The group gets behind Jim's effort and his happy to spend a little time in a small town. Unfortunately, the townspeople don't feel the same way. The group begins to notice that the townspeople are giving them the runaround. Eventually, after some of the group gets kidnapped, Jim forces an explanation out of the mayor. It turns out that the father of Jim's friend tried to keep the townspeople out of the war with the Inbit. He wanted them to leave the fighting to the soldiers. The townspeople wouldn't stand for the interference. In the end, they killed the peacemaker. Jim is disappointed, and ends the episode in a melancholy mood. He decides to keep the book to remember some of the things that the father of his friend stood for.

The group comes to a settlement of soldiers led by the legendary Colonel Jonathan, leader of the famous Mars Base Angel Fang unit. It is not a military outpost, but rather a safe place where they come and relax. Apparently, the Inbit leave the city alone due to the number of soldiers encamped there. In Stick's dealings with the Inbit, he had seen no such fear. He doubts the party mentality of the town. But Stick awe of his hero is greater and agrees to go along on one of Jonathan's missions and is ambushed. Rey and Houquet confront a returned Johnson about what happened to Stick, and he agrees to take them to look him. Quickly they are ambushed by the Inbit, but Houquet arrives in a nick of time to save Rey, only for the pair to be forced to split up. Rey stumbles upon a meeting between a humanoid style Inbit and Jonathan, where the war hero receives some HBT cells. Rey realizes the connection, Jonathan trades his soldiers for the fuel, coming back a hero every time. Upon confronting him, Jonathan tries to justify his actions as keeping the civilian population safe.

While scouting out a new campsite, Stick, Rey, and Mint fall into one of the Invid leader's "Genesis Pits" where she is doing strange experiments. Dinosaurs, monsters, Invid, and possession are all part of the evolutionary experiments conducted by the Inbit leader, the Refles.

The rag-tag group of freedom fighters arrive at the fallback point of the Mars Base Recapture Missions. Unfortunately, the Inbit had arrived earlier and all that remains the invasion force is only a scattered hulks and corpse of ships, mecha and men. Stick was counting on this group is shocked and begins to lose hope in the mission.

A mountain range lies between Stick's group and Reflex Point, a mountain range with an Inbit base right in the middle of it. The group finds that there is a "secret route" through the mountains, but the map that indicates it costs quite a bit of money. Stick's group reluctantly looks for ways to make money.

After receiving a real map of the mountains, the rebels find that the only way through the range is through the Inbit. Stick devises a strategy to attack the base, with some very useful help from Rey.

While camping inside a cave during a sandstorm, the group begins to bicker. Rey ends up being the object of everybody's anger because he gives water to Aisha that no one knew he had. Rey takes the criticism poorly and braves the sandstorm to find more water.

The journey to Reflex Point takes Stick's group through a jungle near a giant Inbit stilt hive. This jungle is inhabited by a primitive tribe of people who worship the gods of the river, and believe that the rebel group has angered the river god.

In a devastated city, Stick's group is driven into the subway by the Refles' new mecha, the Gamo. What's more, they are sealed inside a small section of subway by the Refles' constant effort at their destruction. The Refles is not sure that the freedom fighters are dead, so she orders her Iigaa's to dig through the rubble.

The group of freedom fighters are at the northern tip of what was once called "South America." They devise a plan to cross the body of water between the two continents, using old gasoline driven ships that they found mothballed in a local shipyard. The rebels busy themselves with their preparation for the crossing.

After crossing the Gulf of Mexico, the freedom fighters find themselves in a snowy mountain range. Thinking that they have eluded the Inbit for the time being, Stick's group is in high spirits, joking and eating one of their few decent meals. They do not realize yet that Aisha is an Inbit, and that the Refles is using her to track the rebels.

From the mountains to the desert. A few small towns are eking out a meager existence in the shadow of a huge Inbit transmission tower. Stick and the other rebels, still on their journey to Reflex Point, must find a way around or through the Inbit hive.

Out of the desert, and back into the mountains. The cold has dowsed the spirits of the freedom fighters, just as the constant fighting has. Luckily, while passing through a high mountain pass, Rey finds a huge city buried under an ice canopy.

The rebels are forced to sneak around a deserted town while Mint mourns her destroyed birthday plans. Batra is near, and is easily tricked into retreat by a gadget of Yellow's.

The gang is close to Reflex Point, but they have to deal with a local problem first. A seeming madman is killing all of the soldiers in the sector, and Stick's group vows to end his killing spree. However, after Houquet and Rey have a run in with a mysterious man called Rainy Boy, they begin to doubt the legend of the random killer.

Stick's rebel group is only a day or two away from Reflex Point, but they are badly in need of energy. They stop off in the remnants of New York City. Posing as homeless people, Rey, Yellow Belmont, and Mint find the local Inbit energy cell storage. The group decides to steal some energy cells. Unfortunately, Mint drops some hydrogen canisters, alerting the Inbit to their presence. They are only saved by a would-be actor, who convinces the Inbit that a stray cat was the cause of the commotion.

As the title says, the freedom finally reaches Reflex Point, ready for their assault. However, they are a little late for the assault. An advance force from the Third Earth Recapture Mission had attacked earlier, and by the time Stick's group arrived, they had already been defeated. The ground around Reflex Point is littered with both destroyed Inbit and Mars Base mecha. At first, there are no survivors.

The battle for the Earth begins. Ground troops from the newly arrived human forces have linked up with Stick's band of freedom fighters. Jim has been reinstated in military. All is ready for the attack.

The final episode of MOSPEADA picks up where the last left off. Stick is fighting Batra, and is shot down. Meanwhile, Houquet and Rey climb in their Legioss's, and decide to help Stick out. Jim and Mint vacate the battle scene, Jim is a ground fighter, and the ground attack is over.