Ozark's season 4 trailer announces a big Jonah twist that sets up a very dark future for the Byrde family. The Ozark season 3 finale shocked viewers and characters alike when Marty (Jason Bateman) and Wendy Byrde (Laura Linney) were baptized in Helen Pierce's blood and accepted into Mexican drug kingpin Navarro's (Felix Solis) family. But as the Byrdes climb the ranks of Navarro's drug empire, they also lose their children's trust, with Jonah (Skylar Gaertner) particularly upset with his mother at the end of the season.
In Ozark season 3, Jonah develops a close relationship with his uncle Ben Davis, who eventually proves a liability to the Byrdes. His relationship with Ruth (Julia Garner) leads him to stop taking his meds, and his bipolar episodes start interfering with the Byrdes' schemes. When Ben finds out about Wendy and Marty’s cartel ties, he confronts Helen (Janet McTeer) and outs her real job to her daughter Erin, which eventually leads to her ordering his death in season 3 episode 9, “Fire Pink." This greatly affects Wendy, Ruth, and Jonah. In the season 3 finale, Jonah points a gun at Helen, but the cunning lawyer convinces him it was really his mother who made the final call that killed Ben. It won't be long before Jonah will find a way to betray his family for killing his best friend and uncle.
In the Ozark season 4 trailer, Navarro is heard telling Marty, "your biggest threat will always come from the inside," and this line is juxtaposed over a shot of Jonah. Considering where season 3 left Jonah and his family, it's safe to say this is no coincidence. The trailer also shows Ruth asking Jonah to launder money for her, then Marty unable to conceal his pride for his 14-year-old son who is already laundering money. While this can mean that Jonah will be partnering up with the enemy, this also announces a bigger, darker twist: Marty is raising his son to be a criminal mastermind like himself, in the hope that Jonah can take over the family business should his parents face a tragic end. With the Byrdes already set up as the show's main villains, Marty's pride in Jonah might just be the perfect way to earn him back, securing Jonah's loyalty—and outstanding money laundering skills—till the bitter end.
In the last season, Jonah had a big role in saving his family from the right grip of Helen Pierce. The Byrdes realize they need to make themselves more valuable to Navarro to make him choose them over Helen. The drone video Jonah had of the rival cartel performing a hit on American soil (along with Marty's FBI contact) gets the U.S. Government to remove Navarro's enemy, ending his drug war and saving his children's lives. Marty and Wendy thus climb to the top of Navarro's empire, an unprecedentedly high position of power for them. Maybe even unconsciously, Marty is leading by example and inspiring Jonah to strive for greatness by means of criminal activity.
Ozark season 3 was criticized for failing the Byrde children, not giving them enough screen time, and keeping them mostly confined to the background—especially Charlotte, who spent most of season 3 babysitting Erin. Season 4 will have the opportunity for Jonah to play a huge role, as he betrays his family while Marty prepares him for becoming head of the Byrde family. Ozark season 4 Part 1 will air on January 21, 2022, and it remains to be seen how Marty and Wendy Byrde eliminate their ever-piling threats, and how Jonah will rise to prominence in the shadow of his father, continuing the Byrdes' dark story.