Tread Perilously continues Doctor Who Month with the Twelfth Doctor story "Sleep No More."

Arriving on a space station, the Doctor and Clara learn about the Morpheus sleep compression system. It turns a week's worth of sleep into a five minute investment, allowing people to be more productive! But the side-effects are deadly as a team of Space Marines -- featuring an artificially grown soldier known as Grunt -- discover monsters in the dust of the wrecked station. Will the Doctor uncover the truth about Morpheus? Will Clara succumb to the danger in the corner of her eye? Will anyone make it out alive?

Erik confuses the voice of guest star Elaine Tan with that Jenna Coleman, giving him the fear of double Claras. Erik and Justin discuss the relatively good science in Grunt being based on the female genetic default. Justin points out the wisdom in clearly marking clones and suggests that they should all be made to look like Gary Busey. The pair get lost in a discussion of The Good Place. The episode's resemblance to Aliens, Blade Runner and Alien: Isolation keep them distracted as well. Erik's distaste for the Doctor/Clara by-play comes into focus once again. Justin praises the set design, but will he praise the story overall? Also, Erik points out his own speech impediments.