TMNT (also known as Teenage Mutant Ninja Turtles or Teenage Mutant Ninja Turtles 4) is a 2007 film based on the Teenage Mutant Ninja Turtles franchise. The film sees the Turtles grow apart after their defeat of The Shredder. Meanwhile, strange things are happening in New York City. An army of ancient creatures threatens to take over the world and the Turtles must unite again to save it. It is the first Teenage Mutant Ninja Turtles film made with Computer-Generated Imagery (CGI) by Imagi Animation Studios. The previous films in the series were all-live action. It is the first film in the franchise in 14 years. Chronologically, the film takes place after the original films.The film opens 3,000 years before the late twentieth century, during which time a powerful warlord named Yaotl and his four generals discover a portal opening onto a parallel universe wherein is said to be a great power. Upon opening the portal, the warlord is exposed to this power and made immortal by the contact, but his four generals are turned to stone and his army obliterated. The portal additionally releases 13 immortal monsters that wreak havoc upon the world.
In the twentieth century, the Teenage Mutant Ninja Turtles have grown apart. After their defeat of the Shredder, Master Splinter has sent Leonardo away to Central America for training. The rest of the Turtles have settled into lives in New York:Donatello works as an IT specialist and has become the de facto leader Michelangelo works as a clown called "Cowabunga Carl" for birthday parties, and Raphael continues fighting crime at night while disguised as the vigilante "Nightwatcher". April O'Neil, seemingly expanded from her antique store "2nd Time Around", now operates a company that locates rare relics and acquires them for collectors with the help of her roommate and boyfriend Casey Jones.
While on a business trip in Central America, April meets Leonardo, whom she advises to return to New York, but he is hesitant to do so out of fear that he has not completed his training. April then tells him how the other Turtles have drifted apart and leaves Leo to ponder his next move. April returns to New York with a stone statue for her client Max Winters, the wealthy CEO of a financial empire. Leo stows away on board a plane and returns shortly afterwards. April and Casey deliver the statue to Winters at his corporate office, after they leave he brings all four statues out and reanimates them, revealing that the statues are the four Generals of the myth, and Winters the warlord made immortal. Winters is then visited by Karai and the Foot Clan, whom he hires to scour the city searching for the 13 beasts, who will be drawn to New York by the reopening of the portal, scheduled to happen in days.
Leo returns to the sewer home of the Turtles, where he faces Splinter. Splinter, desiring him to reunite his brothers as a family, forbids the Turtles from fighting until they are cohesive team again. While training, the Turtles encounter one of the thirteen beasts battling with the Foot Clan. Seeing the Foot losing the battle, the Turtles defy Leo and Splinter's orders and engage the beast as well. The beast easily defeats the Turtles; but before it can kill them the four Stone Generals arrive and capture the beast, spiriting it away in a disguised garbage truck. Leo and Raph quarrel, whereinafter Raph leaves to go hunting alone. Later, as Nightwatcher, Raph encounters Casey, who reveals his knowledge of Raph's double identity and joins him in hunting criminals. Together they encounter the Stone Generals again, and are pursued by one until the police interrupt the fight. Raph is knocked unconscious by a dart fired by the Generals, whereupon Casey takes him to his apartment and calls the other Turtles to come and help. While examining Raph, they learn the identities of Winters and his Generals from April. After being revived, Raph leaves them, wishing to fight alone.
Leo, Donny, and Mikey return to their sewer home to plan their next move, where Donny discovers the reopening of the portal will be directly over Winters' Tower. Splinter calls Leo aside and tells him that his team is not complete, and that he knows what he must do. Wishing to preserve their own immortality, which lasts as long as they are made of stone, the Generals plot to betray Winters so as to prevent him restoring their humanity. While looking for Raph, Leo encounters Nightwatcher, whom he challenges. Leo wins the fight, knocking Nightwatcher's helmet off and revealing Raph, who, being resentful of Leo's self-righteous authority, duels with him. Raph ultimately wins when Leo's swords are broken. Raph, horrified by his own rage towards his brother, flees the scene. The Stone Generals then seize Leo, intending to substitute him for the thirteenth missing beast.
Raph returns to Master Splinter and reveals the fight, deciding to make amends by recapturing Leo. Thereafter Splinter and the Turtles, accompanied by Casey and April, travel to Winters' Tower and confront him. Here, the Generals' desire to remain immortal and Winters' desire to send the beasts to their native world are both revealed. Having refused to betray Winters in exchange for immortality, April, Casey, and the Foot Clan search for the thirteenth beast while the Turtles and Splinter fight off the Generals and numerous other monsters emerging from the now open portal. After a long battle and a death-defying search, the Generals are destroyed and the beasts returned to their native world. Winters, now mortal, honors the Turtles and Splinter, thanks them for the fulfillment of his wish, and disintegrates (crosses over to the next life) before their eyes.
As the Turtles regroup, Karai warns them to enjoy their victory while it lasts, on grounds that they will soon contend with a familiar foe (implying the Shredder's return). She and her followers then depart. In the later evening, Winters' helmet, Raphael's "Nightwatcher" helmet, and Michelangelo's clown costume are added to a collection of trophies kept by Splinter which includes Shredder's helmet, the broken canister formerly containing the mutagenic "ooze" which gave the Turtles and Splinter their present forms, and the Golden Time Scepter of the previous films. An epilogue narrated by Raph's voice then shows the Turtles unitedly patrolling New York City, and concludes the film with the much-repeated catchphrase "Oh, I love being a turtle!".