When the Doctor receives a telepathic summons to help out at The Library -- the galaxy's largest repository of books -- he and Donna meet Professor River Song. The archeologist is leading an expedition to The Library as it was sealed 100 years earlier under mysterious circumstances. Of course, that does not explain why Professor Song is so damned familiar with the Doctor. He's at a loss to explain it or why the library insists all the visitors who vanished a century ago were saved. But will he be able to save the Professor's team from perfect predators who lurk in the shadows?
Erik and Justin get into the timey-wimey-ness of it all. They also heap praise on guest stars Alex Kingston and Colin Salmon. Discussion inevitably leads to the strengths and weaknesses of both Steven Moffat and Russell T. Davies. The pair also try to figure out if the number "42" is meaningful to either Doctor Who head writer. Justin tries to imagine what the Fourth or Seventh Doctor would do in this situation. He also gets distracted when he recognizes members of River's team from other TV shows. Erik ends up trying to explain some long-running Doctor Who continuity gaffs and a certain key phrase gets repeated. Also, the Marty Scale makes its Tread Perilously debut.