Batman: The Brave and the Bold Episode 1.09 Journey to the Center of the Bat!

Babyface and his mob break into a candy factory to rob a safe, but are interrupted by the intervention of two heroes: Plastic Man and Elongated Man. As they go after the villains, Elongated Man complains that the public seems to prefer Plastic Man. Plastic Man is more then happy to point out that Batman prefers him as a teammate and they hang out together in their spare time. They take down the mobsters one at a time, and Elongated Man stops Plastic Man when he tries to take some of the loot. When they spot a fleeing Babyface, the two heroes get tangled up and fall into a taffy puller. Fortunately, Batman is there to knock out Babyface and tell them that between the two of them, he prefers to work alone.

Ryan Choi is in his lab working on a vital experiment when he gets a phone call from Aquaman. Batman is next to Aquaman and tells him to get to the point. Aquaman talks about how they were fighting Chemo and Batman took a chemical blast. Ryan Choi transforms into the Atom and rides the phone lines to meet with Aquaman in Bialya. He determines Batman has been infected with a fast-replicating silicon virus. The Atom admits he's a physicist, not a medical doctor, and Batman doesn't have much time. Meanwhile, Chemo is heading out to sea for a nuclear test site. The Atom proposes he goes into Batman's body and Aquaman volunteers himself. Batman insists the Atom will need the muscle. The Atom warns Batman to stay put so his metabolism doesn't accelerate the virus.

The Atom and Aquaman descend into Batman's lung where Aquaman remembers one of his previous missions that the lung reminds him of. Meanwhile, a gradually weakening Batman goes after Chemo while the Navy opens fire without success. Batman closes in but starts to lose motor control and Chemo smashes the Batmobile. Batman submerges the vessel but the ship is leaking oxygen. Batman orders it back to the surface on voice command just in time.

The Atom and Aquaman travel through the villi looking for the silicon virus. They find one of the creatures infecting Batman's body. Aquaman takes them on, summoning a water sword and splitting the first one in half. However, the split pieces grow into separate items. The Atom insists they need to think things through but Aquaman disagrees. The Atom produces an electro-shock gun and fires it at the viruses. He destroys the first wave but a new group appears and the Atom realizes that Batman is exerting himself. Aquaman grabs the Atom and they escape into a blood vessel, where Aquaman telepathically summons a lymphocyte, which he names "Platelet."

Batman continues to draw Chemo's fire and tries to destroy the monster without success.

The viruses close on the miniature heroes and threaten to outnumber them. Aquaman finally takes Platelet through a narrow pass and loses their pursuers. The Atom insists they need to find the seed cell, and it's in Batman's brain.

Chemo finally gets hold of a nuclear missile, and Batman wonders who is guiding him. Right on cue, the Brain sends a message to Batman and tells the Bialyans to surrender. He has Chemo swallow the missile and says that if the country of Bialya doesn't surrender, Chemo will use his internal chemicals to eat through the missile and detonate it. With time running out, Batman ejects from the Batmobile and enters Chemo's body.

Aquaman and the Atom arrive at the brain and find the seed cell. As they approach it, the viruses mutate and grow stronger, and the Atom realizes it's because Batman has been re-exposed to Chemo's toxins.

Chemo marches ashore and assaults the Bialyan city. Inside his chest, the weakening Batman swims to the missile and opens it, then shuts it down. He blasts a whole in the side of Chemo with Batgrenades, freeing himself and causing Chemo to collapse. Batman prepares to take on the Brain and locates his submarine.

The Atom is out of ideas so Aquaman declares it's the time to act. He throws the Atom off of Platelet and draws the viruses' fire.

Batman enters the Brain's submarine and collapses, but knocks over the Brain in the process.

The viruses destroy Platelet, angering the Atom. He launches himself at the viruses, sending them flying. He settles for punching out the creatures and Aquaman joins in. The Atom launches himself at the seed virus and slams his weapon into it, destroying it and its virus minions.

In the Brain's submarine, Batman tries to get to his feet while the Brain rights himself and prepares to kill Batman. Batman recovers from the virus and detaches the Brain's brain from its transport chamber.

Aquaman congratulates the Atom on his heroics but notes he wasn't acting rationally. The Atom says it was a momentary lapse of judgment. Aquaman says that they should honor their fallen mount, Platelet. The Atom directs them out through the tear duct, and all they have to worry about now is getting Batman to cry.