Viewers may be a bit confused at the beginning of The Defenders. "Umm, wait; aren't all four of them supposed to be working together?" you might find yourself saying. It does take longer than some fans might expect for the Defenders to finally assemble, but don't fear: it does happen soon enough! After a few episodes of Daredevil, Jessica Jones, Luke Cage, and Iron Fist doing their own thing, the Defenders join forces at last about three episodes into the new series.
The Defenders starts out with Daredevil, Jessica Jones, Luke Cage, and Iron Fist each picking up where they left off at the end of their respective standalone series: Matt Murdock is trying to wean himself off of vigilantism, Jessica Jones is reluctantly dealing with her new city-wide fame, Luke Cage is getting out of prison, and Iron Fist is heading to America after the attack on K'un-Lun. As each hero goes on their own missions, we actually do see a few meet-ups in Episode 2 — Luke Cage and Iron Fist fight it out over a misunderstanding, and Matt Murdock offers to represent Jessica Jones when she's arrested — but to see all four Defenders get together, you'll have to wait until the end of Episode 3.
All of their solo missions finally lead our four heroes to a shady financial firm called Midland Circle, which we learn is run by the evil organization The Hand and led by the mysterious Alexandra, played by Sigourney Weaver. When a fight breaks out in the boardroom, all four heroes spring into action and wind up meeting one another while beating up a horde of suit-wearing ninjas. I mean, what better way is there to meet some new friends than that?
Though we get to see them fight alongside one another in the final scene of Episode 3, it's not until Episode 4 that we really see the Defenders introduce themselves to one another and lay out their plans going forward. And as you might expect with the prickly personalities involved, not everyone is really on board to start a super-team right off the bat...