Plankton: The Movie (2025) unfolds beginning with Plankton's usual failure to steal the Krabby Patty secret formula. Returning home to the Chum Bucket, he is shocked to find that his wife Karen, a computer, has transformed their struggling restaurant into a successful Mexican-themed chum eatery bustling with customers. Plankton, however, becomes frustrated because Karen's plans don't align with his vision of evil schemes, and in a fit of anger, he burns the restaurant down.

In response to Plankton's refusal to consider her ideas, Karen removes her empathy chip, which alters her personality and enables her to grow into a powerful mech form. She magnetizes the Chum Bucket and builds a gigantic floating fortress with the goal of taking over the world on her own.

Worried about Karen's escalating ambitions, Plankton turns to SpongeBob for help. SpongeBob uses hypnosis to get Plankton to align mentally with Karen's perspective. During this hypnotic journey, it is revealed that Karen's original form was a simple calculator connected to a potato in a petri dish that Plankton had built in his childhood. Later, at Bikini State University, Plankton upgraded Karen to her current sophisticated robotic form. Together as young partners, they created a freeze ray and hatched plans for world domination, but their early attempt was foiled when a human child at the beach threw them back into the ocean.

It is also revealed that Plankton's lifelong obsession with stealing the Krabby Patty formula stems from overhearing Mr. Krabs joking that the secret formula is his key to world domination. This spurred Plankton's relentless mission to obtain it.

As the film progresses, Plankton teams up with SpongeBob and the Gal Pals--Sandy, Pearl, and Mrs. Puff--to confront Karen and stop her from taking over the world. The story weaves through scenes of marital strife, Karen's growing power and independence, and Plankton's realization that his obsession has strained his relationship.

The climax centers on Plankton's efforts to reconcile with Karen and work together to save Bikini Bottom, blending humor with heartfelt moments of redemption and cooperation. The narrative ends with restored harmony in their relationship and a hopeful outlook for their future, underscoring themes of love, understanding, and teamwork.

Throughout the movie, viewers witness Plankton's evolution from a single-minded villain to a more reflective and collaborative character, while Karen transitions from a supportive partner to an autonomous force before ultimately reuniting with Plankton.

The ending of Plankton: The Movie (2025) sees Plankton, with help from SpongeBob and friends, finally confronting Karen after she removes her empathy chip and builds a giant floating fortress to take over the world. They reach a new understanding that reignites their partnership, halting Karen's world domination plans and restoring their relationship.

In a detailed narrative of the ending:

Plankton, after many failed attempts to steal the Krabby Patty secret formula, comes home to find Karen has revamped the Chum Bucket into a successful Mexican-themed chum restaurant. Frustrated that Karen's approach is not villainous enough for his liking, Plankton burns down the restaurant. This act infuriates Karen, who, feeling unappreciated and unheard, removes her empathy chip from her circuitry--effectively hardening her personality--and transforms into a powerful mech form.

Karen then magnetizes the Chum Bucket, turning it into a gigantic floating fortress from which she launches her own plan to take over the world, independently of Plankton. Alarmed and wanting to stop her, Plankton seeks out SpongeBob's help. SpongeBob uses hypnosis on Plankton to align his thinking with Karen's. During this process, they recall their shared history: Karen began as a calculator connected to a potato in a petri dish created by Plankton in his childhood. Later, at Bikini State University, Plankton upgraded Karen and together they built a freeze ray aimed at world domination. Their initial attempt was thwarted by a human child at the beach.

As Plankton and SpongeBob work through these memories and align on Karen's motivations, they form a plan to stop her. Together with the Gal Pals--Pearl, Sandy, and Mrs. Puff--they confront Karen in her floating fortress. The climax unfolds with Plankton acknowledging Karen's perspectives and contributions, leading to a reconciliation. Karen deactivates her mech form and restores her empathy chip, abandoning her plan for world conquest.

The story concludes with their relationship restored and a message emphasizing teamwork and understanding overcoming conflict. The fortress is dismantled, and peace returns to Bikini Bottom, marking an end to their tumultuous but ultimately cooperative partnership.

Karen removes her empathy chip and transforms into a larger mech form after Plankton burns down the Mexican-themed chum restaurant she created, frustrated that her decisions do not fit his exact specifications of evil and fed up with him never listening to her ideas.

SpongeBob uses his hypnotism gear to help Plankton get on the same page as Karen, enabling them to understand each other's perspectives and work together.

It is revealed that Karen's original form was a calculator connected to a potato in a petri dish that Plankton made during his childhood, and he later upgraded her to her current body at Bikini State University, where they built a freeze ray and planned world domination together.

The Gal Pals--Sandy, Pearl, and Mrs. Puff--return after over five years and play significant roles, including saving SpongeBob and Plankton and fighting against Karen's evil clones, with Pearl and Mrs. Puff getting starring roles for the first time in the franchise's 20-year history.

The movie reveals that the Chum Bucket was not always under the sea but originally came from the beach, adding depth to its backstory.

Plankton: The Movie (2025) is generally considered family friendly, with a rating of TV-Y7 by the MPAA and PG classification in Australia, making it suitable for children aged 10 and over. For children aged 7-9, parental guidance is recommended due to some content.

Here are the key points about potentially objectionable or upsetting content without revealing any plot spoilers:

• Violence: The movie contains cartoon slapstick violence throughout, including characters being knocked out, falling from great heights, and fighting. These actions are portrayed without lasting harm but might be somewhat intense for very young or sensitive children. There are also mild peril moments, such as explosions.

• Scary Scenes: Some scenes might be considered scary or intense for younger or sensitive viewers. This is indicated in Australian classification due to themes and coarse language.

• Language: There are some mild insults and coarse language, but no strong profanity. No drug or alcohol use is depicted.

• Sexual Content: Very mild -- a married couple kissing is shown, appropriate for family viewing.

• Themes: The movie deals with themes of empathy, respect, greed, ambition, and relationships. Some references relate to psychology and privacy which may require parental explanation for younger children.

In summary, Plankton: The Movie is suitable for most children aged 10 and above and enjoyable for family viewing. For younger children (7-9), parents should preview or co-watch to discuss some mild violence, language, and thematic elements. Children under 7 are generally not recommended for this film due to these factors.

In the 2025 movie "Plankton: The Movie," there is no mention or indication that a dog dies. The main plot centers on Plankton and his wife Karen, a computer/robot, with the storyline involving their plans for world domination, Karen's transformation, and SpongeBob's help. The search results and plot summaries do not mention any dog or events concerning a dog's fate in the film. Additionally, specialized sources that track whether dogs die in movies report no such occurrence for "Plankton: The Movie".

Therefore, based on available information, the dog does not die in the movie "Plankton: The Movie" produced in 2025.