Martin, son of Luke the Warrior, is captured by the evil Badrang. Seasons later, when Martin gets in a fight with Hisk, one of Badrang's horde, he is tied on top of Marshank in a storm. Bandrang hopes the seagulls eat Martin in the morning. But in the middle of the night, Rose the mouse and her friend Grumm the mole hear Martin crying out in the storm; the reason she and Grumm go to Marshank is to rescue her brother, Brome, who was captured by Badrang. She calls out to Martin whether he has seen him. She tells Grumm that they should help the poor mouse. So in the morning they use slings to ward off the seagulls to hope to free Martin, somehow.....
As Martin and his new friends languish in Marshank's Prison Pit, Rose and her companion, Grumm, hide from Clogg's advancing seaborne corsairs. Badrang and Clogg finally meet, pretending to be the other's friend, but they both soon skirmish and Clogg retreats intending to take Marshank from his rival. Druwp, one of the slaves, become a traitor to Badrang; he identified the slave ringleader to him. As Badrang posts extra guards the news reaches Martin. Outside, Grumm conspires with Rose to tunnel to their rescue.
Meanwhile in the prison pit, Brome tells of his and Rose's home, the idyllic region called Noonvale. If his father the chief can be alerted, he will surely rescue them. Grumm continues to dig hard to complete the tunnel. Under the cover of Clogg's battle against Badrang Grumm breaks into the Prison Pit to help Martin, Brome, and Felldoh escape.
Martin demonstrates he is a born leader, and everybody sees it. Rose sees something else in Martin.
Martin and friends survive the storm, but become separated from Brome and Felldoh.
Martin and friends continue on toward Noonvale. Clogg plans to double-cross Badrang.
As the Mirdrop threatens to destroy Martin and friends, Rose rushes the monster with a thick branch.
Martin and his friends are captured by Slo Worms and are dragged into the lizard's lair.
Martin tries to help the warden, who is under attack. He and his friends are then attacked by the Gawtrybe.
Brome and Felldoh attempt to get the slaves to safety when they learn Clogg and Badrang formed a truce.
The owl Boldred shows Martin and friends the way to Noonvale.
Rose leads Martin and his friends to Noonvale and find out that Brome has not made it back.
Just as the Fur and Freedom Fighters arrive, Felldoh dies. The battle rages until Badrang offers a deal.
Martin and Rose confess their love for each other before tragedy strikes. Martin leads the troops to victory.