Miss Carew: "You see I did a bad thing, Miss Cooper, I sold my soul… to the Devil."
Despite the giveaway episode-title, it takes the script 26 minutes to get to the above line, however let's bear in mind that in this Miss Carew actually neither sells her soul, nor has any actual dealings with Satan. (unless we're going to get all judgemental about her death at the end)
Presumably set after The Dead Line, The Devil And Miss Carew is about an alien somehow offering life to the terminally ill in exchange for help invading Earth. It's a thin story, and does very well for it. Not very much actually happens, enabling the main players to come to the fore through plenty of dialogue.
There is a tiny bit of suggestiveness, but as with the last radio series, this is thankfully the family-friendly version of Torchwood again. The absence of zombies also benefits it, forcing Miss Carew to actually have some motivation for her complicity. There is still the usual machine to save Earth at the end, but since it's really Miss Carew's failure to fix it that solves everything, that's not quite the same deal. The play's opening location of a nursing home is close enough to a hospital for it to count though.
Nothing special, but nothing terrible either. Funnily enough the same day that I listened to this I had coincidentally already watched A Pinky And The Brain Halloween, which conversely did feature the duo selling one of their souls to the evil one.
In fairness, no other series is going to compare well after that.
Gwen: "Well, whoever he is, you're under his control, aren't you?"
Miss Carew: "No! No-one controls me. Everything I do is of my own free will."
Gwen: "If you were acting of your own free will, I don't think you'd be kidnapping people and locking them in your basement."