本季情节贴合80年代的标志性事件，包括核战电影《浩劫后》（The Day After）的上映、前总统里根的星球大战演说、大卫-科波菲尔让自由女神像「消失」的神奇魔术。第四季的核心情节是「这个苏联间谍家庭如何生存（如何自保）」。与此同时，被囚禁在俄罗斯的双重间谍Nina有可能重返美国，与前情人Stan Beeman团聚。请注意这个「有可能」，因为现在谁也说不准。Jennings家的小儿子Henry本季有更多出境时间，他在前两集中经常与邻居Stan待在一起。上一季关注了Paige的变化，或许这一季要关注Henry的变化？此外，Keri Russell的怀孕不会写进剧情中。FX暗示该剧可能在本季或者第五季结束。
“In the early 1990s, at the height of the international war on drugs, the government agency in charge of Britain’s borders, Her Majesty’s Customs and Excise, realized that they were losing the battle against drug smuggling. Their solution was extraordinary,” reads the logline. “In a top-secret operation, a small team of British Customs employees were sent undercover. Their task – to infiltrate Britain’s most dangerous drug gangs.” “They were not trained spies. These were ordinary men and women, plucked from ordinary lives around the U.K, put through a basic training regime then told to build new identities in the criminal underworld. These identities were called Legends.
改编自维克托·拉瓦列2013年的小说《The Devil in Silver》。聚焦搬运工人Pepper（丹·史蒂文斯 Dan Stevens 饰），因为坏运气和坏脾气，他被送到了一所名为New Hyde的精神病院，里面满是被社会遗忘的人。Pepper想要获得自由，就必须面对与他作 对的病人、怀着阴森目的的医生，甚至恶魔本人。这里是地狱般的地方，任何事情都不是表面那样，Pepper必须直接面对一个以New Hyde里人们的苦痛来蓬勃壮大的存在，但这样可能会证明：最可怕的恶魔恰恰是他自己。
