WARNING: The following article contains spoilers for Ant-Man and the Wasp, in theaters now.
Fans were left a bit disappointed when it was revealed Paul Rudd's Ant-Man, aka Scott Lang, didn't have a role in Avengers: Infinity War. Given the big part he played in Captain America: Civil War, fighting for Steve Roger's side and cementing his status as an Avenger (albeit a rogue one), many figured he'd be a shoo-in to stand alongside Earth's Mightiest Heroes once more when Thanos invaded.
Well, while that wasn't meant to be, there was some consolation gained knowing Scott would take part in Avengers 4. With Ant-Man and the Wasp set just before Infinity War, though, director Peyton Reed needed to accomplish a few things. The first thing he does is explain why Scott wasn't involved in the fight against the Mad Titan, as he's busy rescuing Janet Pym (Michelle Pfeiffer) from the Quantum Realm.
Secondly, and more importantly, Reed cleverly uses this flick as a vehicle to set up Ant-Man's role in Avengers 4 when the fight resumes against Thanos and his galactic conquests.
Early on, we learn Scott took a plea deal following the events of Civil War. He's basically a fugitive after breaking the Sokovia Accords, but unlike most of Cap's other allies such as Black Widow and Falcon, Scott has a family, namely his daughter Cassie, to consider. That's why he cuts said deal, goes under house arrest, and isn't considered for duty when Thanos' forces come for the Infinity Stones.
However, the exact timeline of Reed's film and when it syncs up with Infinity War is clarified during the movie's game-changing post-credits scene. As Team Pym -- Hank (Michael Douglas), Janet and Hope (Evangeline Lilly) -- send Scott back into the Quantum Realm to harness its energy, he suddenly loses radio contact with them from within the microverse.
As his distress calls unsuccessfully go out, the camera cuts to Scott's allies -- or, rather what remains of them. Instead of finding Scott's crew scrambling to help him out, we see everyone's ashes crumbling in the wind. That's right, the radio silence is due to Team Pym all dying thanks to Thanos' famous snap. But, even though it seems Scott is lost in the microverse, Reed creates an opening for him to appear in Avengers 4, and most importantly, with a few trump cards up his sleeve.