In the pilot episode, we see approximately thirty years into the future, where an aging Batman is having increasing difficulty handling criminals he once subdued with ease. One night, a heart attack forces Batman to betray a lifelong principle by threatening a criminal with a gun, despite already wearing a new, high-tech Batsuit. Subsequently, Bruce Wayne decides to retire the Batman persona, and crime fighting in general, permanently.
The story then fast-forwards another twenty years. Gotham City is now a futuristic megalopolis equipped with staggering high rises and hovering/flying vehicles. Bruce Wayne is now a virtual recluse, spending his later years living in bitter isolation with no companion but his guard dog, Ace. It is implied by virtue of his continuing to fight crime long after he should have, and his retaining of the costumes worn by Robin, Nightwing, and Batgirl, that even before he had a heart attack, something horrible transpired that caused Bruce to sever his ties with the Justice League and forbid his disciples from ever again assuming their alter-egos. The events which caused all of this was finally revealed in Batman Beyond: Return of the Joker.
In 2040, Terry McGinnis (born on August 18, 2023) is an athletic sixteen year-old high school student, and reformed troublemaker with a deeply ingrained sense of personal justice. During the pilot episode, he saves a fellow passenger on a commuter rail from being hassled by one of the Jokerz, and later single-handedly takes on an entire gang of them to defend his girlfriend, ultimately resulting in a harrowing high-speed motorcycle chase through Neo-Gotham's expressways. The chase ultimately ends at the doorstep of Wayne Manor, where a fleeing Terry runs into the elderly Bruce Wayne. Bruce and Terry fend off the Jokerz side-by-side, but the exertion aggravates his heart condition. Terry helps Bruce back to the manor, and while staying there, he discovers the entrance to the Batcave, and later returns to "borrow" the Batsuit to avenge the death of his father. As crime and corruption are beginning once again to rear their ugly heads in Gotham, Bruce ultimately allows Terry to assume the mantle of Batman.
Terry continues the battle against crime tutored by Bruce, and aided by a new high-tech Batsuit that augments his abilities, fires Batarangs from the wrists, flies using jets fired from the feet, allows eavesdropping through a hypersensitive touch microphone, and provides camouflage abilities. He comes to have his own rogues gallery, such as the seductive shape-shifter Inque, the hypnotist Spellbinder, the bitter, deaf sound expert Shriek, the deadly assassin Curare, the insane terrorist Mad Stan, the African hunter Stalker, a reincarnation of the Royal Flush Gang, and The Jokerz, a gang idolizing the Joker. However, on occasion, Terry is also forced to face his mentor's old foes, such as the atrophying Mr. Freeze, Bane (elderly, wasted, and dying from his consumption of Venom, the substance that gave him his strength), the immortal Ra's al Ghul, and even a reborn Joker.
Terry's initial greatest foe is Derek Powers, a ruthless billionaire who took over Wayne Industries and was later accidentally mutated into a radioactive monstrosity known as Blight. Powers had Terry's father, Warren McGinnis, murdered after Warren discovered that Powers was in the process of developing a biological weapons program. The first season ended with a showdown between Batman and Blight aboard an abandoned nuclear submarine, where Powers was in hiding after his identity as Blight was revealed to the world by his ambitious son Paxton Powers, who planned to usurp his father as chairman of Wayne-Powers.
Maxine "Max" Gibson (born October 28, 2023) is a seventeen year-old computer genius who discovers Batman's secret identity, and helps Terry with everything from computer hacking, to babysitting, to coming up with excuses for Terry's girlfriend, Dana Tan. Max plays an integral part in Batman's war on crime, essentially as his Alfred.
Terry also finds one other ally, though a begrudging one: Barbara Gordon, the former Batgirl. Having followed in the footsteps of her father, James Gordon, Barbara is now Police Commissioner of Gotham City. In one episode, Barbara reveals to Terry that she and Bruce had once been romantically involved. However, she is unhappy with the idea of a new Batman, especially a teenager, as she is still haunted by the same event that caused Bruce to go into isolation. However, knowing from personal experience that she cannot deter Terry anymore than she could have been deterred from being Batgirl, she relents, possibly also out of respect for her mentor and former lover, the original Batman. Also, passing conversation between Barbara and Bruce suggested that at the time of Batgirl's retirement, the suit had bullet holes in it that had been repaired.
Trivia
Batman Beyond: As mentioned in the Comic Books section, it's shown at the end of season one's "Shriek" that Bruce has it all figured out.
Bruce Wayne: The voice kept calling me Bruce. In my mind, that's not what I call myself.
- Interestingly the DCAU seems a little vague on the subject. For instance, whenever Bruce/Batman was feeling particularly depressed (such as in the Justice League episode "Hereafter"), he'd lose the deep "Batman voice" and revert to the soft style of speaking he always reserved for "playing" Bruce.