Counterpart is an American science fiction thriller television series starring J. K. Simmons.

The OI oversees a checkpoint below its headquarters between parallel Earths (the "Alpha" and "Prime" worlds).

The parallel Earths were created in 1987 during an experiment by East Germany when only a scientist named Yanek was on-site.

Matters escalate during the series when a powerful rogue faction on Prime executes long-simmering plans to get revenge on Alpha.

[39] While the reasons for her departure were never publicly stated, Berg implied it was due to conflicts with creator Marks who wanted full control of the series and to be the sole showrunner.

The site's critical consensus reads, "Tense and gripping, Counterpart is an absorbing thrill-fest led by J. K. Simmons' multi-faceted dual lead performance.

[48] Alan Sepinwall of Rolling Stone was less favorable with the second season and noted how the series had become too convoluted and difficult to follow.