Tread Perilously continues its examination of Doctor Who's 23rd season, "The Trial of a Time Lord" with parts 5-8: Philip Martin's "Mindwarp."

Continuing his case, The Valeyard introduces into evidence The Doctor's visit to Thoros Beta; where he and Peri discover the leader of the Mentors needs a new body to continue an important trade deal with a nearby star system. The Doctor appears to sell out Peri to save his own skull when the Mentors' scientist suggest they can transplant their leader's brain into The Doctor's head. Chaos reigns as a revolution led by King Ycarnos (guest star BRIAN BLESSED!!!!) upsets the Mentor order just as the Doctor is abducted by the Time Lords to begin his trial. Will Ycarnos be able to end the Mentor threat without him?

Justin comes around on Peri. He is also convinced that The Valeyard is a Peeping Tom. Guest actor BRIAN BLESSED!!!! receives nothing but praise for his performance. Erik tries to make sense of some of the episode's most nonsensical moments. They pair also discuss the pronunciation of "Crozier" and the vaguely racist Native American costumes on some of the aliens. Justin also determines that BRIAN BLESSED!!!! is a huge fan of Shaquille O'Neal's Kazam. Also, Doctor Who reminds them that the Matrix never lies.