The first episode of Marvel's Secret Invasion series was a solid start to a spy series that could upend the Marvel Cinematic Universe, in which a group of extremist shape-shifting Skrull refugees are plotting to take over Earth and, in the process, kill the humans who live there. It's well-written, the cast is uniformly great, it doesn't look like it was shot on an extremely fake-looking CGI soundstage. I can't help but hope that this will be a rare Marvel season that manages to start well and then maintain its quality.

But the first episode of Secret Invasion also gave me a feeling I've been getting from the MCU a lot over the past few years: Why wasn't this story ever set up or teased before now? There have been 11 movies and eight seasons of TV that have come out since the Skrulls were introduced in Captain Marvel, but all that Marvel has done with them since is to very occasionally remind us that Nick Fury's green pals are still around. And there's been nothing, meanwhile, about these secret other Skrulls who are doing that titular invasion.

Warning: This article contains light spoilers for the first episode of Secret Invasion, and it also discusses major plot details from some past Marvel series, like The Falcon and the Winter Soldier and WandaVision.