Transformers: The Last Knight recently (as in, like, two days ago) began filming in Cuba, with a small crew shooting a few scenes before principal production moves to Detroit on June 6. With that in mind, a new viral video for the fifth installment in the franchise is hinting at the arrival of something big on May 31 — which could very well be the first official teaser.

That would be an incredibly quick turn-around time for a teaser, but Michael Bay is known for nothing if not giant robots, absurd action, patriotism, montages of oily-muscled dudes, and…oh, right, his efficiency. Yes, that. Anyway, here’s the mysterious viral teaser from the official Transformers Twitter account:

The morse code translates to “E I’M COMING FOR YOU MAY 31.” Who is E? I guess we’ll find out on May 31. It’s possible that we’re getting a brief teaser for the film, which hits theaters on June 23, 2017 — though that seems a bit early. Another possibility is that Paramount will reveal more official cast members, as very few have been announced so far.

Mark Wahlberg is reprising his role as Cade Yeager from Age of Extinction, with Josh Duhamel returning as Lieutenant Colonel William Lennox, last seen in Dark of the Moon. Isabela Moner is set to play a new female lead named Izabella, with Neighbors star Jerrod Carmichael in an unknown role. Michael Bay is directing Transformers: The Last Knight from a screenplay by Art Marcum and Matt Holloway (Iron Man) with Ken Nolan (Black Hawk Down).

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