WGN America's historical wartime drama Manhattan returns for its second season on Tuesday, Oct. 13 at 9/8c. The show's creator Sam Shaw, alongside executive producer Thomas Schlamme, and cast members John Benjamin Hickey, Rachel Brosnahan, Ashley Zukerman, Katja Herbers, and Christopher Denham took the stage at the Television Critics Association fall previews to discuss which historical events would propel the show's upcoming season, where our favorite characters are when the show returns, and what new faces might appear to cause more trouble for them.

Manhattan's first season followed the race between two teams--Frank Winter's (Hickey) ragtag group and Reed Akley's (David Harbour) better-funded, better-equipped team--to build the first atomic bomb. The problem with that, of course, was that if either team succeeded in their missions, it would be a magnificent feat for science, but also a horrible tragedy the world would likely never come back from. The explosive finale ended on a cliff-hanger after Frank's guilty conscience led him to plant a false confession detailing a scheme between himself and Akley that ultimately ended up saving Charlie's (Zukerman) butt, while putting Frank's in danger.

When the series returns, it's safe to say that the tension will remain at 11 as the show continues to tell a morally gray story about this complicated time in American history, a story that still resonates today as the 70th anniversaries of the bombings of Hiroshima and Nagasaki draw near.

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Just as the first season centered on building the bomb, Season 2 will be organized around the Trinity Test, the detonation of the world's first atomic weapon on July 16, 1945, at the U.S. Air Force base in Alamogordo, N.M. The season will cover a span of 15 months, with one episode featuring a six-month time jump, according to Schlamme, who also revealed that Daniel London's Robert Oppenheimer, a character who danced around the periphery of Season 1 as a symbol of the work the scientists were doing, will play a much larger role going forward.

Also in Season 2, Frank will have had what Hickey described as an awakening. "In some very, very surprising ways, [Frank] does a big 180," Hickey said, comparing the character's arc to Newton's third law that says for every action there is an equal and opposite reaction. "He finds himself every bit as ruthless [as he was in Season 1 but] in the opposite direction. He's the same guy; he's just seeing the world in a different way."

Meanwhile, Charlie will become "less cerebral" and "less questioning" of the events of Los Alamos following the shocking events of the finale.

"We don't know whether he's going to save the world or end it," hinted Zukerman. "And we don't know why he's doing it: for the world or for himself?"

A little less cryptically, Brosnahan said her character Abby, the wife of Zukerman's Charlie, will stop being reactive and become a willing participant in her life. "You start to see the emergence of a much more active Abby, of someone who's determined to find her place in this [world] and [who is] asking deeper questions about her role in it."

Manhattan's cast is growing in Season 2

Viewers will likely be unsurprised to find that Herbers' character, Helen Prins, the lone female scientist on Frank's small team, will become even more determined to do the best work she possibly can after the events of Season 1.

"She wants to be defined by her worth as a scientist and not by her gender," said the actress. "[She also] wants to secure a job for after the war. She's aware that maybe wartime, ironically, is her time. She might not have gotten a job like this were it not for war. It might have gone to a man."

Perhaps the biggest surprise of Season 1 was the reveal that Denham's character, Jim Meeks, was a spy. Denham says that in Season 2 "we don't know yet to whom he's passing [secrets], nor what his motivations are," but that his actions are likely linked to the fact that he lost his best friend, a Chinese American and a former member of Frank's team, who was murdered by the government when they believed he was a spy.

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Elsewhere in Season 2, the show will welcome new cast member William Petersen as Colonel Emmett Darrow, a new high ranking officer at Los Alamos who believes the bomb is "going to be a force of good" for America.

"He's certainly an obstacle and he is a different kind of force who enters the world of the show," said Shaw. "He sort of represents the future, he's a guy who has his eye on the prize of a different American century to come, a different world order."

Manhattanreturns Tuesday, Oct. 13 at 9/8c on WGN America.