Scott has lost a lot of time in his adventures in the Quantum Realm.
He never got to see Cassie Lang, his daughter, grow up.
The glowing device on the table is a beacon, and it's transmitting a message to the quantum Realm.
Whatever message was being transmitted, Janet Van Dyne, the original Wasp, doesn't seem happy about it.
It seems like Cassie might have done something to set off the beacon.
The beacon sucks all of the Pyms and the Langs into the Quantum Realm.
We get our first glimpse of Kang in action. He gives Scott Lang an offer that he can't resist: All the time that he has lost.
The trailer also gives us our first glimpse at Chronopolis, Kang's stronghold in the Quantum Realm.
Despite everyone warning Scott Lang not to trust Kang, he wants what he is offering him.
Kang's offer turns into a threat, as Scott must bring him something he wants or die.
It looks like the Quantum Realm is starting to break down.
The many iterations of Scott Lang seem to be unraveling, an unfortunate omen for the plot of the film.
Kang might be an antagonist that Ant-Man and the Wasp, and all the Pyms and Langs combined, can beat.