Frank Spotnitz has fled the “High Castle.”

The showrunner of “The Man in the High Castle” — described as perhaps the most ambitious original series yet from Amazon Studios — has abruptly exited the project, TheWrap has learned.

Spotnitz, a veteran writer-producer who worked on “The X Files” and numerous other series earlier in his career, left in the middle of production on Season 2 of “High Castle,” an alternative history about what would have become of the United States if the Nazis had won World War II.

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It’s unclear what that will mean for the show, which is being produced in Vancouver, Canada.

“High Castle” is based on a 1963 alternative history novel by classic science-fiction writer Philip K. Dick.

The series was described as the most-watched since Amazon began making original series.