(CNN) A tale of two series: "Mr. Robot" returns with a spring in its step Sunday, clicking on all cylinders in gearing up toward its finish; while "The Walking Dead" lumbers into its 10th season, hitting familiar notes, with another major cast defection to come.

After a lengthy 22-month layoff, USA's "Mr. Robot" begins its fourth and final season with Rami Malek coming off an Oscar win , and with a renewed sense of urgency in its dense, conspiracy-minded plot.

At the same time, the new season finds shifting alliances, augments its narrative with sharp flashbacks that flesh out some of the characters -- with especially good material involving BD Wong, who plays the mysterious Whiterose; and Michael Cristofer, as ruthless CEO Phillip Price -- and still revels in dark humor and a general creepiness that consistently keeps the audience off balance.

Malek's skilled hacker Elliot Alderson remains the centerpiece, even if he often seems caught up in events that are way over his head -- and distracted by the fractious nature of what's going on inside it, as he wrestles with his outspoken alter ego Mr. Robot (Christian Slater).

Without giving anything away, the new season includes further insight into the underpinnings of E Corp -- the shadowy conglomerate that serves as a front for a much larger web of corruption.

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