In the episode, Helen Magnus (Amanda Tapping) awakens in a future where Earth is devastated by a plague that turned all but a handful of the human population into savage zombie-like creatures.

To give the practical sets a more post-apocalyptic feel, the production crew added several wrecked cars and several bags full of dead leaves.

While venturing the streets, Magnus finds herself under attack by a savage humanoid creature, but is saved by two men in Hazmat suits, who proceed to capture and decontaminate her.

Unlike his original personality, Zimmerman is acting far more violent and aggressive, and believes Magnus to be an imposter, citing she died three years ago.

As more creatures attack the base, Magnus escapes and returns to the Sanctuary, where on the way she is joined by a young girl, Jessica Mitchell (Nicole Muñoz).

Now believing Magnus is who she says she is, Zimmerman recounts the events of the plague to her; ten years ago, a contagion was released in Old City, transforming humans to cannibalistic creatures.

When containing the city failed, the disease spread throughout the globe and despite her best efforts, Magnus could not find a cure and was eventually killed in Buenos Aires.

Magnus realises that before the outbreak began, she was on a mission in Honduras; tired of losing people she loved, most recently daughter Ashley,[1] she was researching for a way to "cure" her immortality.

The ending, where Magnus is transported from the post-apocalyptic future to the present, was written in a way that Kindler wanted the audience to discuss whether it was a case of time travel or merely a "psychological dream.

[2] Also because of this, and the inclusion of an "assault" of a naked woman, considered taboo by the producers, Kindler did not want to include those scenes in any future episodes.

Because the producers believe the audience could misconstrued the scene as Magnus being raped, before shooting the sequence Tapping asked director Brenton Spencer not to make it sexual in any way.

One can easily forgive the show, of course even at its nadir, it's just too harmless to hate, and as a one-off riff, it could be worse.A drop of almost 200,000 viewers from the previous episode, "Hero",[9] "Pavor Nocturnus" was viewed by 1.420 million Americans, making Sanctuary the sixth most seen series from Syfy the week it aired, and was the second highest viewing the day it aired, behind Stargate Universe.

Dunne's portrayal received a mixed response, stating "the script doesn't give him much to do besides bark out exposition and snarl with hatred at the faceless enemy," though he and Tapping did "succeed in evoking an entire end-of-the-world scenario with just a few terse lines of dialogue.

"[8] In review of the first and second season releases on Blu-ray Disc, Michael Simpson of CinemaSpy named the episode "Sanctuary's take on I Am Legend", but thought the plot was "derivative".

[11] In review of the second season, David Blackwell of Enterline Media named "Pavor Nocturnus" as a standout episode, along with "Veritas" and "Haunted".