Another Sentinel One-like computer, known as the Prime Sentinel, has been compromised by an evil unknown force, and the Sentinels journey into space to fix the problem.

When an alien plant spore is brought to Earth by a returing space probe, it endangers the planet when it begins to grow uncontrollably. The Sentinels must consult a wise cosmic sage before deciding on a course of action.

Anubis is revived and wants to exact revenge on human beings. The Sentinels have to stop this from happening.

The Sentinels have to deal with giant tough-to-beat robots who are initially after some gold as fuel.

A human from an advanced time period has returned to stop the construction of a moon base by destroying the supply rockets (unmanned) shortly after launch.

A large section of the north pole has vanished, and the Sentinels are dispatched to investigate.

A powerful human from another dimension is freed and sends Hercules and Mercury into his dimension which allows him to steal their spaceship and use it in an attempt to conquer his original dimension that he came from.

A young girl who has telepathy and can control wild animals, is attacking a laboratory in a forest. The Sentinels are dispatched to investigate.

Astrea is kidnapped with the intent to use her to power an underground civilization against her will. Hercules, Mercury, Sentinel One and MO use their spaceship to burrow their way to the city to rescue her.

Another sentinel with an evil alignment and who has the power of Astrea, Hercules and Mercury combined, comes to Earth for revenge.

The Sentinels travel to an alternate universe to investigate and defeat a device that alters reality.

An eco-terrorist threatens civilization and the Sentinels travel into the ocean to find and stop him.

A large planetoid is on a direct collision course with earth. The Sentinels come to the conclusion that the planetoid must be destroyed to save the earth, so using their spaceship, they intercept the planetoid and find out that further investigation is needed.