More than three decades ago, Stephen King published a short fantasy novel called The Gunslinger in a limited run. Though King indicated at the time that the book was part of a larger story called The Dark Tower, few could have expected what was coming. Over the next 30 years, King published seven more Tower novels, creating a world that not only dwarfed his other stories but often also swelled to contain them. The Dark Tower now stands as King’s longest and most ambitious work. It’s a magnum opus that’s part dimension-hopping epic fantasy, part Western and part post-apocalyptic drama. It’s also the most important King work that’s never been adapted for the screen.

A decade ago, rumlings of a Dark Tower film began. They were replaced by rumblings of a film series bridged by TV series. But quickly found its way to hell. The project changed studios, changed directors and changed stars, until finally it seemed to really be happening. Tower fans have been waiting so long for this that even the photos of stars Idris Elba and Matthew McConaughey in costume didn’t seem like enough proof that the film was real. Now, at long last, we have footage to prove that The Dark Tower is coming.

Elba and McConaughey each dropped a 15-second teaser on their respective Twitter pages Tuesday, announcing the arrival of a full Dark Tower trailer tomorrow. The clips are little more than snippets of dialogue, but at this point, even a glimpse of footage is enough for fans who thought this day would never come.

If you’re still somehow uninitiated, The Dark Tower is an epic quest story with the fate of all things hanging in the balance. It follows Roland (Elba), the last in a line of gunslinger warriors (think Arthurian knights with revolvers instead of swords) as he journeys to the titular Tower, the nexus of all worlds and all things. Opposing him is The Man In Black (Mcconaughey), a dark sorcerer who’s worn many faces over the ages and aims to bring the Tower down. Along the way, the two men cross dimensions into our world. Roland meets new friends and his quest grows ever-more complex. It’s like nothing else King’s ever written and that’s a good thing.

Look out for the full trailer tomorrow. The Dark Tower hits theaters August 4.