The episode introduces guest star Amy Acker as Audrey Nathan, who was first mentioned in The Avengers as "the cellist".

"The Only Light in the Darkness" originally aired on ABC on April 22, 2014, and according to Nielsen Media Research, was watched by 6.04 million viewers.

After arriving at Providence, Grant Ward tells Phil Coulson's team that he failed to stop the Fridge raid, but claims that he killed John Garrett.

Intending to recapture Fridge escapees, Coulson takes Ward's quinjet to Portland, Oregon, along with Leo Fitz, Jemma Simmons, and Antoine Triplett, to apprehend Marcus Daniels, who can absorb energy and attack others using Darkforce.

Skye convinces Koenig to help her hack the NSA so they can review the CCTV footage of the Fridge raid to try to trace the escapees.

Coulson, Fitz, Simmons and Triplett later return to Providence and are confused to find no sign of May, Ward, Skye, Koenig, or the Bus.

In March 2014, Marvel revealed that the nineteenth episode would be titled "The Only Light in the Darkness", and would be written by Monica Owusu-Breen, with Vincent Misiano directing.

[1] Executive producer Jeffrey Bell, on the decision to introduce the character known previously in the MCU only as "the cellist" here, said, "there's that one line and suddenly it's who is this person?

"[2] In March 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.

Once the scene had been cut together, McCreary wrote a piece of music that "97%" matched Acker's visible movements, including timing and pitch.

A particularly tricky moment had the character suddenly stop playing on the arrival of Brennan's Daniels, with Byers trying "a dozen different versions" before he and McCreary were satisfied.

McCreary stated that the biggest challenge "was to take all those constraints and compose a piece of music that satisfied them all and yet felt soaring and lyrical.

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] The poster for "The Only Light in The Darkness", created by Pascal Campion, focuses on Coulson and his cellist lover, Audrey, while also hinting at the villain for the episode, Marcus Daniels.