"Sneak Peek" is the eighteenth episode of the second season of Batman Beyond. It depicts the near revealing of the secret identities of Batman. A mysterious man who is completely intangible is stalking Gotham, recording secrets wherever he can find them. These secrets are later displayed on a tabloid news show The Inside Peek by Ian Peek. Terry thinks the show's great until he finds that his secret will be revealed as well.
Ian Peek introduces another episode of The Inside Peek where he reveals the secrets of Gotham's elite. He prattles on about how the trainer of a heavyweight boxer is flirting with the boxer's girlfriend, how Rocker Jamie Jerald is illegally getting spliced, and, for the headline story, Paxton Powers's indecent behavior at a private party.
Matt McGinnis eagerly watches this last segment, but his mother angrily shuts off the television. Terry, nearby, tells his mother to lighten up, it's just entertainment. She retorts that "you wouldn't find it so entertaining if you were on the receiving end."
After wrapping up his show, Ian's producer asks him how he manages to get such exclusive footage, but Ian says it's a "trade secret."
Later that night, a crime boss, Jimmy Lin, sneaks into City Hall for a meeting with D.A. Sam Young, to secretly testify about his gang's activities. Lin is anxious that he will be found out, but Sam assures him that they are completely alone. Neither of them know that Lin has been followed into the building by a mysterious man seemingly composed of flashing blue and black matter, capable of passing through walls. Unnoticed by either man, the mysterious figure films Lin's testimony, until Sam sees him and summons a guard. The mystery man manage to disable a guard, then Batman arrives. Batman attacks, but all his punches seem to pass through empty air, while the mystery man shows himself perfectly capable of hitting Batman. Finally, he starts a fire and escapes, entirely unharmed by the flames. While Batman is down, the man touches a device on his belt, switching off the blue and black energy field and revealing himself to be Ian Peek.
In physics class at school, Terry learns that solid matter is mostly composed of empty space, and asks if it's possible for some objects to pass through others. His teacher explains that most scientists believe that to be impossible, but there was one who thought otherwise. Later, Terry talks to Bruce, who reveals that the man worked for Wayne Enterprises: Nobua Taka, a research scientist who believed he could "phase" molecules to allow them to pass through solid matter. However, Taka can't be the mystery man, as he died in a fire years ago.
The Inside Peek comes on again and Ian Peek reveals the events of the previous night, telling about Lin's meeting with Young. Terry realizes the connection and heads out to see Peek. His show finished, Peek starts complaining about stomach problems. Batman confronts him at the studio, but Peek denies any knowledge. However, before Batman can further interrogate him, Lin and a gang of thugs enter and try to kill Peek. Batman stops them but loses sight of Peek, who escapes and plants a camera on the Batmobile. Unaware of the camera, Batman returns to the Batcave, talks to Bruce and removes his mask. All of this is caught on tape by Peek.
That morning, Terry wakes up to find his mother and Matt watching a teaser for Peek's latest show that will air that evening, in which Peek promises to reveal the secret identity of Batman and his mentor. Bruce has already discovered it but can do nothing. Terry goes to see Peek who is still having trouble with his stomach. Terry pleads with him to leave Bruce out of it, but Peek smugly refuses.
However, after Terry leaves, Peek takes a tablet for his stomach pains, and hears it drop. He looks down in horror and sees that his body is partially "phased" even without the belt.
Terry returns home and finds that both Matt and Mary are excited about seeing the show (Mary appears to have forgotten her earlier indignation). Deciding its best they learn the truth from him first, Terry confesses that he's Batman. His mother and brother both laugh in obvious disbelief.
The show starts to come on, but is suddenly postponed. Terry goes to investigate.
Bruce appears at Peek's studio in response to Peek's urgent summons. Peek says his body is slowly becoming completely intangible, even without the belt. Peek demands that Bruce use his company's resources to find a cure. Bruce wants to know why Peek came to him, and Peek confesses that he stole Taka's research and prototype belt, and also set the fire that killed him.
Disgusted, Bruce refuses to help him, and Peek threatens to expose both him and Terry. Bruce calls his bluff and keeps walking, and Peek, desperate, tries to give back the footage, but Bruce still refuses. Enraged, Peek attacks and nearly kills Bruce but Batman arrives and saves him. Peek continues to fight, and raises a gun, but his finger, and then his whole hand, become intangible, followed shortly by his entire body. He sinks through the floor, yelling for help. Batman tries to go after him and just manages to reach the lowest basement level as Peek is sinking through it. For a moment, it seems that Peek will be able to escape but he loses all tangibility and sinks into the ground, laughing maniacally. Bruce explains that he'll keep falling until he reaches the center of the earth: "That's about as inside as you can get."
- During the pan of the Batcave, the suit next to Batgirl's is supposed to be Nightwing's but its symbol is red.
- This episode is another example of what is sometimes called the "Ghost Paradox" in science fiction and fantasy: if a person is rendered completely intangible by scientific means, he should logically be unable to stand on a floor, breathe air (which is a gaseous matter) into his lungs, or speak; yet Peek is shown doing all of these things. Also, if such a person ceases to be tangible matter, then gravity would have no effect on him.
- The Gray Ghost's costume can be seen in the Batcave during the scene when Terry calls Bruce but receives no answer.
- The scene were Terry confesses to being Batman was used for several TV spots promoting the show on Kids WB.
- Jimmy Lin isn't alone in not wanting to face tax evasion charges. In "Joker's Millions" even the Joker didn't want to face them.
- Bruce seems to have lost his moral rule of saving all lives possible. In the past he'd even save the Joker, an insane mass murderer. Now, he refuses to help Peek, an amoral reporter.
- The camera used by Ian is similar to that used by Terry in "The Last Resort."
Bruce: I always assumed I'd be found out sooner or later. It's just galling that a piece of garbage like Peek had to be the one.
Terry: I don't care what you do to me. But he doesn't deserve this. He's done too much for this city to wind up in the middle of a media circus.