Dean meets Len (Jared Gertner) a Lizzie Borden fan who says he saw a girl named Amara wandering outside the hotel a few nights ago and he hasn't felt normal since he met her.
Suspecting Dawn to be soulless as well, the Winchesters track her down and find her and her lover dead in a house with Jordie tied up.
Aside from fleshing that out, the episode was entertaining -- the Lizzie Borden red herring was a smart touch – but the Darkness didn't come across as very threatening in her current incarnation.
"[6] Sean McKenna from TV Fanatic, gave a 4.3 star rating out of 5, stating: "That said, putting Sam and Dean at the core focus of the hour felt like some old school Supernatural.
This was an entertaining episode that found a solid way to put the brothers on the trail of their monster of the week while incorporating the bigger story.
"[4] MaryAnn Sleasman of TV.com wrote, "Episodes like 'Baby' and 'Thin Lizzie' are not a complete return to original form for Supernatural because that move would be a disservice to the series as well; Hell, Purgatory, the cage, all manner of possession, betrayal and loss — it can't be ignored, but as we enter what is certainly edging on twilight for our little undead show, we also can't ignore just how unsustainable the endless suffering is.
"[7] Becky Lea of Den of Geek wrote, "The wider season arc is developing nicely, especially the focus on how the Darkness is affecting the world as we know it, both actively and indirectly.
Although I personally would have preferred a singular episode, using a seemingly straightforward case to illustrate what Amara is up to and clue the boys in on to how she is developing is a streamlined way of advancing that narrative arc.
Sam and Dean are now as up to speed as Crowley and it gives the show a template to move forward with as they 'follow the bodies' to catch up with the speedily growing Amara.
Next week sees Castiel contact Metatron for help with the Darkness so we're back in deep season Big Bad territory.