The fun... uh, make that trouble begins when Scott's daughter, Cassie (Kathryn Newton), develops a beacon that's capable of signaling the Quantum Realm, the tinier-than-tiny dimension that's been nothing but bad news for their allies, the Van Dyne family. That's where Janet (Michelle Pfeiffer) was imprisoned for decades while her husband, Hank (Michael Douglas) and daughter Hope aka The Wasp (Evangeline Lilly) gave her up for lost.

Small wonder that Janet looks positively horrified when she learns of Cassandra's invention. And those fears turn out to be well-founded when the device promptly sucks them all into the Quantum Realm with no way back to terra firma. Now they have to negotiate their way through a dangerous landscape populated by new foes and friends, including a yet-to-be-named character played by Bill Murray — who makes a prominent appearance in the trailer on the heels of real-world allegations of misconduct on the set of a different movie.

But the most dangerous foe by far is someone passing himself off as a friend. While in the Quantum Realm, Scott and Cassie cross paths with Kang, who MCU fans previously met in the Season 1 finale of Loki in one of his other multiversal identities. And he's got an offer the heroes may not be able to refuse, especially as Scott's life appears to be in danger. "I can get you home," says Kang. "And give you more time — if you help me. So, what's it going to be Ant-Man?" Needless to say, he makes the idea of "help" sound pretty sinister.

Having assisted in saving the world in Avengers: Endgame, it's a particularly cruel twist of fate that Ant-Man may now be dooming it. Looking ahead in the MCU timeline, we'll be seeing Avengers: The Kang Dynasty in 2025, which means the foundations of that dynasty are laid here. And fans on Twitter agree that what might seem like a small family adventure is going to have big implications going forward.