Clark Gregg reprises his role as Coulson from the film series, and is joined by principal cast members Ming-Na Wen, Brett Dalton, Chloe Bennet, Iain De Caestecker, Elizabeth Henstridge, and Nick Blood.

That month, guest star Lucy Lawless's role was revealed, building hype for her appearance, although her character was always intended to be killed off at the end of the episode.

Series composer Bear McCreary used Christopher Lennertz's Agent Carter theme when writing the music for this sequence.

"Shadows" originally aired on ABC on September 23, 2014, and according to Nielsen Media Research, was watched by 5.98 million viewers, considerably less than the first season premiere.

Mechanic Alphonso "Mack" Mackenzie questions why Coulson would risk lives just to steal a quinjet, but Coulson explains that they need its ability to literally disappear, something they currently cannot do themselves following the injuries engineer Agent Leo Fitz recently suffered at the hands of Ward; he now struggles with technology and hallucinates the presence of Agent Jemma Simmons, who left S.H.I.E.L.D.

[2] In September 2014, Marvel announced that the premiere episode of the season would be titled "Shadows", to be written by executive producers Jed Whedon and Maurissa Tancharoen, with Vincent Misiano directing.

"[4] Speaking about the reveal that Fitz was just imagining the presence of Simmons due to the injuries he sustained at the end of the first season, Tancharoen said, "We didn't want him to come out of that experience unscathed.

[8] About the decision to cast Lawless as Hartley, who was always intended to be killed off at the end of the episode, Whedon said "We wanted you to invest in the character and feel like this person was a real equal to Coulson.

"[5] At the 2014 San Diego Comic-Con, Nick Blood and Reed Diamond were announced as cast in the roles of Lance Hunter, a mercenary, and Daniel Whitehall, a member of Hydra, respectively.

[8] In September 2014, Marvel confirmed that all principal cast members from the first season (Clark Gregg as Phil Coulson, Ming-Na Wen as Melinda May, Brett Dalton as Grant Ward, Chloe Bennet as Skye, Iain De Caestecker as Leo Fitz, and Elizabeth Henstridge as Jemma Simmons) would return, that Blood would join them for the second season.

They also confirmed that Diamond and Lawless would guest star in "Shadows", along with B. J. Britt as Antoine Triplett, Adrian Pasdar as Glenn Talbot, Henry Simmons as Alphonso "Mack" Mackenzie, Patton Oswalt as Billy Koenig, Wilmer Calderon as Idaho, Brian Patrick Wade as Carl Creel, Matthew Glave as Roger Browning, and Simon Kassianides as Sunil Bakshi.

[12] A still image of Atwell's cameo was released on September 10, 2014, revealing that Neal McDonough and Kenneth Choi would also be appearing in the episode.

[13] Composer Bear McCreary changed his synth programming for the series from "warm, round tones" to a "mangled under heavy distortion" sound.

Then, "just as the audience begins to get used to" the orchestral sound, the episode cuts to "modern day and suddenly I bring in the new synths, with distorted basses blazing over the nastiest groove I've ever written for the show.

McCreary also introduced a new Hydra theme in the episode that represents Daniel Whitehall, and is used in scenes featuring the Obelisk and Carl Creel.

He did note that the episode "did little to actually give Hunter or Mack distinguishing personalities [sic]" and stated "I don't really buy that Fitz would even be there, working alongside the team, at this point.

"[21] Marc Buston for Den of Geek scored the episode 4.5 stars out of 5, feeling that the series had finally reached its potential by incorporating Marvel elements such as Creel and Whitehall, while also creating a darker tone and developing the original characters.

"[22] James Hunt, also for Den of Geek, gave a positive review as well, stating "The momentum of last season's finale hasn't been lost, and indeed, it's even been added to.

[24] Alan Sepinwall at HitFix called the episode a promising and lively start to the season despite a lot of exposition, "helped by some good casting and smart creative choices".

He was positive about both the changes to the existing characters and the introduction of the new ones, especially Creel, and though he noted that the opening sequence was "itself a piece of brand extension—early promotion for Agent Carter," he felt that "links to the rest of the Marvel [Cinematic] Universe are always welcome when they're in service to the story the show is telling".

Club graded the episode a 'B−', feeling that "With a clearly defined villain and mission statement, this show's second season is already off to a better start than its first year, but there's still plenty of room for the series to grow.

"[26] Kathrine Siegel of Paste gave a negative review of the episode, calling it "pretty flat, and very disappointing as season premieres go", feeling that the character development and plot were limited, lamenting the decision to kill off Lawless' character, and stating that the episode continued a trend of the series having "amazing individual parts [that] never come together to create a solid whole.