Trapped on the ocean floor, Leo Fitz and Jemma Simmons send out a distress signal, and devise a controlled explosive to blow the windows open and escape.

After being saved from death by Raina's synthesized GH325, John Garrett begins exhibiting the super-strength given by the Centipede serum, as well as the manic behavior and hypergraphia caused by GH325, and the symbols he carves resemble those found in an earlier mission by Grant Ward in the Todorov Building in Minsk.

[a] Coulson, May, Skye and Triplett use the Trojan to locate the new Cybertek facility, and launch an assault while Ian Quinn is giving some military generals a tour.

In the aftermath, the Centipede soldiers are arrested by the military, Coulson takes Ward captive, and Peterson, unable to face his son, leaves to seek redemption for his crimes.

Under cover of his apparent death, Fury heads to eastern Europe to continue hunting Hydra, while Coulson, May, Skye and Triplett use co-ordinates in the toolbox to locate another secret base, the Playground, where they reunite with Simmons and meet Billy Koenig, identical brother of the deceased Eric.

In April 2014, Marvel revealed that the twenty-second episode would be titled "Beginning of the End", and would be written by executive producers Maurissa Tancharoen and Jed Whedon, with David Straiton directing.

[2]: 192 In April 2014, Marvel revealed that main cast members Clark Gregg, Ming-Na Wen, Brett Dalton, Chloe Bennet, Iain De Caestecker, and Elizabeth Henstridge would star as Phil Coulson, Melinda May, Grant Ward, Skye, Leo Fitz, and Jemma Simmons, respectively.

[1] It was also revealed that the guest cast for the episode would include Bill Paxton as Agent John Garrett, J. August Richards as Mike Peterson / Deathlok, B. J. Britt as Agent Antoine Triplett, Ruth Negga as Raina, David Conrad as Ian Quinn, Glenn Morshower as General Jacobs, Josh Daugherty as Kyle Zeller, Patton Oswalt as Billy Koenig, Mark Berry as Admiral Jolnes, Jeffrey Muller as Kaminsky, Ajani Wrighster as Ace Peterson, Asif Ali as Jesse Fletcher, Kyla Garcia as Mrs. Zeller, Nicole J. Butler as Aunt Mindy and Cynthia Rose Hall as employee.

The production team tried to pair specific artists to the teaser posters based on their previous work and how it connected to the themes and emotion of the intended episode.

[8] Phantom City Creative director Justine Erickson said, "It made sense to bookend the series with a poster that on one hand called back to where they began, but more importantly showed how far they've come as a team."