The super-villain training academy known as H.I.V.E. Academy presents three of its finest cadets for their first mission. The H.I.V.E. Headmistress gives a demonstration of the powers of Jinx, Gizmo and Mammoth to one of the organization's clients – the mysterious mercenary known only as Slade. Slade decides that for their final exam, they need to fulfill one simple task – destroy the Teen Titans.
At Titans Tower, the teenage superheroes engage in their everyday lives. Cyborg and Beast Boy argue about the location of the remote control. Robin and Starfire have a discussion about lightspeed travel while the curmudgeon Raven grimaces perpetually. After finding their refrigerator was full of with blue, furry food, the Titans decide to go into town for pizza. While at the pizza parlor, they are set upon by the three students of the H.I.V.E Academy. Gizmo disables Cyborg's robotic systems with a power scrambler and Jinx goes one on one with Raven. Mammoth accomplishes little, but does succeed in causing significant collateral damage to the nearby surroundings. Gizmo succeeds in removing Cyborg's right arm and Jinx uses her magic to propel Beast Boy, Raven and Starfire into the river. During the fight, a massive hole is opened up in the ground and Robin falls in. When the Titans regroup, they discover that Robin is missing.
Having soundly defeated the Titans, the H.I.V.E. decides to take control of their headquarters, Titans Tower. They arrive just as the Titans return home and the fight is quick and decisive. Jinx hurls a wave of magic that sends the remaining Titans flying away from the tower. Claiming it as their new home, they immediately begin renovating the Tower, transforming it into a giant letter "H". Gizmo has Cyborg's right arm mounted on the wall as a victory trophy. Jinx moves into Raven's room and tries on Raven's cloak, while Mammoth gorges himself on the strange blue food that he finds in the refrigerator.
Back on the mainland, Robin appears and rejoins the group. He comes up with a plan to take back the Tower. Cyborg is still remotely linked to his missing limb, and activates an electronic eye in one of its fingers. The arm removes itself from the wall and plugs itself in to the Titans computer mainframe whereupon it deactivates the Tower’s security systems.
The Teen Titans return, determined to taking back their home. They engage in a fight with the young supervillains and manage to succeed in defeating them. Robin grabs Gizmo by the neck and interrogates him, forcing him to reveal the person responsible for setting up these attacks on the Titans. Gizmo sneers and drops the name "Slade". Robin has no idea who Slade is, but is anxious to find out. As the Titans send the H.I.V.E. members packing, they set about repairing the damage to the Tower. Cyborg still cannot find the TV remote but soon realizes that it has actually been placed in its proper location. Raven is irritated that somebody was in her room, citing that "Nobody goes into my room". Beast Boy suffers the most traumatic revelation as he discovers that all of his compact disks have been categorized alphabetically. Robin however, is still concerned over the identity of Slade.
Later, back at his hidden subterranean lair, Slade watches footage of the H.I.V.E.'s battle with the Titans. He is pleased to know that the Titans received his "message".
The title refers to Jinx, Gizmo, and Mammoth's final task being to destroy the titans.
Slade: If your students are going to serve me, they have to pass one final exam: destroy the Teen Titans!
Jinx: (after bringing bad luck to Beast Boy) This just isn't your lucky day.
Robin: Sorry to interrupt the victory celebration, but like I said, this isn't over.
Cyborg: We're just getting started.
Starfire: (To Raven) I do not understand. How could you not find him? People do not just vanish! He has to be someplace, so go there and look!
Starfire: (To Cyborg, who is trying to repair himself) Perhaps I could be of some assistance.
Cyborg: I got it.
Starfire: But you are so damaged and -
Cyborg: I got it!
Beast Boy: Hey! She only wanted to help! What is your problem?
Cyborg: What do you think? We got kicked out of our house, a pint-size Poindexter took me for a joyride, and in case you haven’t noticed, I just became left-handed!
Raven: Enough! We need to control our emotions.
Cyborg: Or what? Our bad vibes will keep you from meditating?
Starfire: I wish Robin were here.
Cyborg: Well, he’s not! Don’t you guys get it? They won, we lost. IT'S OVER!!
Beast Boy: Is it me, or are we getting our butts kicked?
Robin & Raven: It’s just you.
CYBORG:Maybe I should call me Flyborg. I was halfway to Gotham city before Star got that thing of my back.
- "Final Exam" is frequently thought of as being the first Teen Titans episode.