This week’s episode of Murdoch Mysteries ventures into darker territory, at least as far as this season so far is concerned. Micheal Seater returns as the devious and nefarious James Gillies in a tense piece scripted by Peter Mitchell and Paul Aitken. Murdoch (Yannick Bisson), Brackenreid (Thomas Craig) Crabtree (Jonny Harris), Ogden (Helene Joy)…