This article contains spoilers for Locke & Key season 2.
Locke & Key season 3 will be completely different since the series has moved beyond the comics. The success of the Marvel Cinematic Universe has brought comic book adaptations to the mainstream, and that doesn't just mean viewers are watching traditional superhero adventures. Take, for example, Netflix's Locke & Key - a dark supernatural adventure in which a group of children is plunged into a world of magical keys and deadly demons. The series is based on the dark comic book stories of Joe Hill and Gabriel Rodriguez, and the Locke & Key season 1 performed so well Netflix renewed it for two more seasons. Season 2 is now available for streaming, and Locke & Key season 3 has already wrapped production.
Locke & Key season 3's story will presumably pick up from the dramatic ending of season 2. This saw the Lockes confront Dodge in a spectacular final battle that pitted one set of keys against another, with the children emerging victorious but at a terrible price. Things are changing at the Keyhouse in the wake of Dodge's defeat, with Bode deciding to use the Memory Key on their mother, Nina, so she can finally make sense of her life, while a heartbroken Tyler decides he wants to forget all about the keys forever. But they don't know that another Echo has been summoned from the past, Captain Gideon, the first demon to emerge from the Black Door. The ending of Locke & Key season 2 sets up a third season that will be very different from what has gone before and will be very different from the comics, as well.
There's a simple reason for this; Locke & Key season 3 has gone beyond the comics. Locke & Key: Alpha #2, which ended the threat of Dodge, at last, was published back in 2013. More recently, speaking at San Diego Comic-Con 2019, Joe Hill did indeed announce that the story would continue; called World War Key, this was expected to run for thirty-seven issues across six titles, and it would revisit the Revolutionary War, the Civil War, and World War II. Hill described it as "about the idea that the past is never gone... and I think a lot of ghost stories are about ways the past keep bleeding through to the present." Thematically, these sound similar to Locke & Key season 3, which will clearly focus on a Revolutionary villain who has been brought into the present. But Locke & Key season 3's story will be different, simply because flashbacks to 1775 in previous issues have already confirmed Captain Gideon doesn't exist in comic book lore. This is an entirely original story, even if thematically it's similar to the narrative Joe Hill is working on.
No doubt there will still be familiar aspects of Locke & Key lore in season 3, though. Many new keys were introduced in Locke & Key season 2, and it's reasonable to assume there will still be more discoveries in season 3. Given the themes, one of the most likely keys to be discovered is the Timeshift Key, which, when turned in the grandfather clock in the Keyhouse, allows people to view the past. This could be extremely useful for the Lockes, helping them come to understand their new enemy.
Locke & Key season 2 honored the spirit of the comics rather more than the letter of them; in truth, that's the reason it worked so well because it has dramatically reinvented its source material to make the story work on the small screen. Locke & Key season 3's story will have even more creative freedom, changing the Locke & Key comics and taking its heroes on journeys their comic book iterations will never experience.