It's official: AMC is moving forward with its Walking Dead companion series in a major way.

The top-secret drama, which went through the pilot process with the title of Cobalt (and Fear the Walking Dead), will join the flagship series on the network as the cabler continues to focus on scripted fare. In addition to ordering the pilot to series, AMC has preemptively renewed the drama for a second season. The first season will consist of six hourlong episodes — just like the flagship series did. The drama will premiere on AMC in the "late summer," with season two set for 2016.

Robert Kirkman, who created The Walking Dead comic series, co-wrote the pilot with Dave Erickson (Sons of Anarchy). Kirkman and Erickson exec produce alongside Walking Dead's Gale Anne Hurd and Dave Alpert. Erickson serves as showrunner, while Adam Davidson directed the pilot. Walking Dead VFX guru Greg Nicotero will also exec produce the series.

While AMC has been tight-lipped on the series' premise, sources tell The Hollywood Reporter that the drama is a prequel that takes place in Los Angeles at the onset of the zombie outbreak. AMC on Monday confirmed that the companion series is set in Los Angeles but revealed nothing more beyond that it will focus on new characters and storylines. The drama is still untitled.

Read more AMC's 'Walking Dead' Prequel: All the Details (So Far)

Cliff Curtis (Gang Related) stars as Sean Cabrera, a teacher who shares a son with his ex-wife. Sons of Anarchy's Kim Dickens is set to co-star as Nancy, a guidance counselor who works at the school with Sean and is seeing him romantically. Frank Dillane (Harry Potter and the Half-Blood Prince) co-stars as Nancy's son Nick, who has battled a drug problem. And Alycia Debnam Carey (Into the Woods) is set as Nancy's ambitious daughter Ashley, who is the polar opposite of Nick and has dreams of leaving L.A. for Berkeley when the apocalypse strikes.

See more 'Walking Dead' Comes to Life: From Comics to the Small Screen

The Walking Dead companion — first announced in September 2013 — could give AMC a zombie drama in every quarter, given the six-episode freshman season's summer bow. The flagship, which resumes production in the summer, airs the first half of its season in October and the second half in February. The offshoot series comes as The Walking Dead evolved to megahit status. The zombie drama, overseen by showrunner Scott M. Gimple, ranks as TV's No. 1 drama series among the advertiser-coveted adults 18-49 demographic.

“We take incredibly seriously the notion of building a satisfying companion series to the No. 1 show on television. From the beginning of The Walking Dead on AMC, we’ve been asked questions about what was going on in other parts of the zombie apocalypse, and what it looked like as the world really did 'turn.' Through this new series, we’re going to find out,” AMC president Charlie Collier said in making the announcement Monday. "Robert Kirkman, Dave Erickson and their writing team, along with an incomparable set of producers, cast and crew have created something remarkable and clearly distinct. We respectfully follow the request of Monty Python as we bring out (the latest of) our Dead.”

“We feel empowered by this two-season commitment, a serious show of faith from our network partner AMC,” Kirkman said. "I personally take it as a sign that they believe, like we do, that we've accomplished our goal of developing something original that can pay tribute to the original show and expand the world I created while at the same time having something new to say with this story. I’m very grateful that we now have the opportunity to tell this amazing story and show the fans that we really haven't scratched the surface yet when it comes to The Walking Dead.”

AMC Global — the cabler's international network, has acquired the international televisions rights to the series, which it will air within 24 hours of the U.S. premiere — something Fox International Channels does with the flagship series.

The new series comes months after AMC opted to focus on original scripted fare and ditched nearly all of its unscripted programming (save for Comic Book Men and Talking Dead). It joins a roster of dramas including the fifth and final season of Hell on Wheels, Halt & Catch Fire, Turn, Better Call Saul (already renewed for a second season), Badlands (due in late 2015/early 2016), Humans and Night Manager as the network looks to its future beyond Mad Men.

On the pilot side, the network has Afghanistan drama White City and controversial comics adaptation Preacher in the works. The latter, which recently earned a pilot pickup, is in consideration for 2016.

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For comics scribe Kirkman — who oversees Image Comics imprint Skybound — the Walking Dead companion gives him three scripted shows on cable after his most recent comic-to-TV entry, Outcast, was picked up to series at Cinemax. (He has four total, including Talking Dead, which he exec produces.) On top of that, Kirkman's Image/Skybound title Thief of Thieves is in development at AMC with Alpert attached, and Kirkman is attached to executive produce an adaptation of David Schulner's comic Clone for Universal TV and Syfy.

Email: Lesley.Goldberg@THR.com

Twitter: @Snoodit