The first television spot for "Transformers: The Last Knight" delivers a sinister Optimus Prime, hammering home the tagline "Rethink Your Heroes."

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The 13 seconds of footage juxtaposes the image of a blue-eyed Optimus in the beginning with a purple-eyed depiction of the Autobot as he seemingly delivers a deathblow to fan favorite Bumblebee, which is sure to fuel theories that the one-time hero is the victim of mind control.

The fifth film in the blockbuster Paramount Pictures franchise, the plot details of "The Last Knight" remain a mystery, despite the release of a trailer that depicts scenes from medieval Europe and World War II. Michael Bay's final "Transformers" film as director, it's intended to lay the groundwork for a planned expansion of the $3.78 billion series that includes a Bumblebee spinoff slated for 2018, another Transformers sequel in 2019, and a possible origin movie for the constantly warring Autobots and Decepticons.

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According to producer Lornezo di Bonaventura, "The Last Knight" is designed to "open a really large universe of what Transformers is, and where they’ve come from, and how we relate to them, and how they relate to themselves.”

Opening June 23, “Transformers: The Last Knight” stars franchise veterans Mark Wahlberg, Stanley Tucci, Josh Duhamel, Tyrese Gibson and John Turturro, joined by newcomers Isabela Moner, Liam Garrigan, Jerrod Carmichael, Mitch Pileggi, Laura Haddock, Santago Cabrera and Anthony Hopkins.