Tread Perilously starts a month of British telly with the sci-fi classic Sapphire & Steel and parts 1 & 2 of their "Assignment 3."

Sapphire and Steel are summoned to an apartment block where strange time disturbances have been detected. But the apparent source of the trouble is a vacant flat. Meanwhile, a family unit consisting of a woman, a man, and a child are becoming increasingly agitated by strange noises, a lack of communication from their home base, and the sudden desire to murder one another. And since their home is identical to the flat Sapphire and Steel investigated, where are they? Or, perhaps, when are they? Will time give them time? Or will it make lovers feel like they've got something real?

Justin tries to make sense of the characters and the premise. He also tries to understand the brutalist architecture of mid-20th Century England. Erik gets lost in the square footage of what he considers to be a luxury flat. Justin determines Garth Marenghi's Darkplace is a direct parody of Sapphire & Steel. A reading of Joanna Lumley's CV sounds a little too made up for Justin's liking. He also tries to make sense of David McCallum's hairstyle. Joy Division becomes an important cultural touchstone and pillows turn into murderous swans.