This direct to video animated movie is based on Grant Morrison and Adam Kubert's 2006 comic book storyline arc, "Son of Batman" which introduced Damian, the biological son of Batman and Talia, the daughter of his nemesis Ra's Al Ghul. This storyline itself was drawn upon events in the Mike W. Barr and Jerry Bingham's 1987 graphic novel, "Batman: Son of the Demon" in which Talia became pregnant with Batman's child only to suffer a miscarriage which caused her to lose the child. Morrison's retconned version claimed that Talia deceived Batman about her miscarriage in order to secretly raise their son as her father's heir only for Damian to ultimately reject his mother (and grandfather's) to become the newest Robin, following in his father's footsteps.
During Deathstroke's raid on Ra's Al Ghul's temple where his League of Assassins train, Ra's Al Ghul confronts Deathstroke who has a helicopter fire a missile inside the temple. As Ra's Al Ghul is dying, Deathstroke tries to end his master's life. However, Damian protects his grandfather and manages to stab Deathstroke's left eye. After Deathstroke's group left the temple in a disarray, Damian and Talia find Ra's Al Ghul dead, just inches away from the Lazarus Pit. Talia decides to put Damian into Bruce Wayne's care since he will be safer there.
In Gotham City, Talia saves Batman from Killer Croc, and later in a disclosed place, she informs her beloved about their love child, Damian. Talia leaves the two to exact vengeance on Deathstroke. While Damian gets adjusted to life in Gotham and his father's ideals of justice, he tracks down Ubu who is out picking up harlots. When Ubu is overwhelmed by Damian's attacks, Ubu makes a run across the streets. Damian catches up and dishes a can of whoop ass on him. Damian demands Ubu to explain where Deathstroke is. Not getting any answers from Ubu, Damian prepares to execute Ubu. In the nick of time, Nightwing, swoops in and knocks the prepubescent boy. He playfully mentions how the psychopaths are getting younger these days. Afterwards, Nightwing is being patched up by Alfred. Damian mocks Nightwing, but he cannot forget that Nightwing defeated him.
After Deathstroke has beaten, torture, and kept Talia in custody, Batman and Damian find out Deathstroke's location when they save Dr. Langstrom who had been dong the man bat experiments. Damian receives a message from Deathstroke, a challenge and a location to save his mother. Deathstroke tells Damian to come alone and leave the sperm donor out of their fight. As soon as Batman realizes Damian is gone, Damian arrives at the drill site in the Indochina sea. Deep underground, he confronts Deathstroke who has his mother at gun point. As Damian drops his weapon, Deathstroke fires at Damian, but he hits Talia who protected her son. Batman arrives on scene and uses a device that emits a loud frequency, sending all the man bats flying out of the cave. After knocking down Deathstroke, Batman rushes to Talia's side. Damian spots Deathstroke fleeing from the scene and chases the man down. During Deathstroke and Damian's fight, Damian somehow defeats Deathstroke with a broken arm. He tricks Deathstroke into cracking a glass pipe that fires a stream of hot, green liquid.
With the fight over, Nightwing rescues Batman, Damian, and Talia. Talia asks Damian to join her. Damian refuses his mother's offer after being changed by his father's ideals.
- Jason O'Mara as Batman
- Stuart Allan as Damian Wayne
- Morena Baccarin as Talia al Ghul
- Giancarlo Esposito as Ra's al Ghul
- David McCallum as Alfred Pennyworth
- Xander Berkeley as Kirk Langstrom
- Thomas Gibson as Deathstroke
- Sean Maher as Nightwing
- Bruce Thomas as James Gordon
- Fred Tatasciore as Killer Croc