Apple TV just wrapped up the third season of its hit sci-fi series Silo, with a fourth and final season already dated for summer next year.

But it seems the streamer has more ambitious plans yet. According to reliable Apple TV reporter Sigmund Judge, Apple is working on a spin-off show that could go into pre-production later in the year.

Apparently, the spinoff will be based on an upcoming Hugh Howey novel, centered on the happenings in Silo 40.

While Apple has not confirmed the plans, and although Howey is publicly denying it, there is one little detail that makes this seem very plausible: the Silo sets have not yet been deconstructed.

Typically, a show with no planned future (either ended or cancelled) will quickly tear down and sell off sets in order to make room for something else on the production lots. However, Judge reports that filming on Silo season four ended in March, almost six months ago, and yet the sets remain standing.

This is very good evidence that Apple plans to re-use them in the future, probably for the spin-off reportedly currently in development.

We have already seen Apple invest heavily in its science fiction franchises with spin-off series like Star City (from the world of For All Mankind) and an announced upcoming series set in the Monarch universe.

And Silo has clearly been a big viewership hit for the streamer, so it makes sense to keep the content coming.