Tread Perilously's month of Doctor Who adventures continues with the 1974 story, "The Ark in Space."

When Harry hits the wrong switch on the TARDIS console, he, Sarah, and the Doctor end up on Nerva Beacon, a space station returning to Earth orbit after thousands of years. Its purpose: to repopulate the planet after it was scorched by solar flares. But the mission has been co-opted by the parasitic Wirrn, who have their own designs on the Earth. Can the Doctor convince the Nerva crew he is not a primitive? Will Harry learn his chauvinism has no place in the 20th or 50th Centuries? And will bubble wrap ever get such prominent use on Doctor Who again?

Erik and Justin get lost in the bubble wrap of it all. Precarious special effects, RP accents, and solid acting make this one of the most Doctor Who episodes Justin has ever watched. He immediately takes a dislike to Harry, who is ill-served in this Robert Holmes script. Jamie McCrimmon is fondly remembered for his more liberated views on women's roles in time travel. For some reason, Erik thinks he can attempt a Tom Baker accident. The pair try to remember the term "transmat" and, for once, the corridors get high praise.