Reports began to surface this evening via social media that a trailer for Bad Robot’s upcoming mystery project is attached to screenings of Michael Bay’s 13 Hours: The Secret Soldiers of Benghazi. The film is titled 10 Cloverfield Lane, and while many suspect it’s a secret Cloverfield sequel, there is some evidence to support that this not quite true, including a statement from J.J. Abrams himself. So what is 10 Cloverfield Lane, exactly?

I attended a screening of 13 Hours tonight and saw no such trailer, but several people who attended screenings elsewhere tweeted about a mysterious preview for a film called 10 Cloverfield Lane. Obviously, with that title, the immediate assumption is that this is a sequel to Matt ReevesCloverfield, produced by Abrams and Bad Robot. That film had a similarly enigmatic marketing campaign, and while the trailer for this new project isn’t yet available online, there are a couple of “trailer reviews” from fans on YouTube.

Slashfilm did a little digging and came to the conclusion that 10 Cloverfield Lane is actually the secret Bad Robot project from director Dan Trachtenberg, who previously helmed the popular Portal: No Escape short. The movie was originally operating under the title Valencia, though that appears to have been a code name. As to why this movie invokes the Cloverfield name…

Collider was able to get this official statement from Abrams via Paramount, which confirms that this is not a sequel to Cloverfield, though — as the title suggests — it is definitely related:

The idea came up a long time ago during production. We wanted to make it a blood relative of Cloverfield. The idea was developed over time. We wanted to hold back the title for as long as possible.

Here’s what we do know about 10 Cloverfield Lane / Valencia: it stars Mary Elizabeth Winstead and John Goodman, and tells of a woman rescued from a car accident by a doomsday prepper who keeps her in his basement, claiming that he’s saved her from a chemical attack that’s rendered the outside world unlivable.

Also of note is that the original teaser trailer for Cloverfield debuted in front of Michael Bay’s first Transformers film back in 2007, which is a nice callback. 10 Cloverfield Lane is set to hit theaters on March 11, so we should see the official trailer arrive online pretty soon, probably before the end of the week.