Now, now! Twist the dials!
The First Doctor and his companions, having left China behind, find themselves once more at the mercy of the wonky time mechanism in the TARDIS, arriving on a glass sand beach surrounded by acid seas. Over those seas and far away are the titular Keys of Marinus, four of which this fab foursome will be coerced into finding.
Much like the preceeding “Marco Polo,” Terry Nation’s “The Keys of Marinus” (Story Production Code E) is a sweeping epic of a story, stretching a simple “fetch and carry” plot over six episodes. Four Keys must be found, each in a different location on the planet Marinus and each accompanied by a different type of story. Finding the first Key involves psychological suspense, with a struggle to separate reality from illusion. And there are brains in jars.
The second Key is in an overgrown laboratory with violent plant life, and in finding it, Ian and Barbara undergo a horror-type encounter with eerie whispering from creeping vines. To find the third Key, Ian, Susan, Barbara, and two new helpers run around a frozen waste in an action episode, fending off wolves, a burly trapper, and ice warriors who come to life when heated up. And the acquisition of the fourth Key requires solving a murder mystery that is nowhere near as puzzling as the very awkward jump between episodes four and five, when we go from Ian escaping the trapper’s hut to Ian being knocked out in a vault with no explanation.