WARNING: The following contains spoilers for The Third Day, Season 1, Episode 6, "Last Day -- The Dark," now airing on HBO.
HBO's The Third Day is a very thought-provoking journey, dissecting the concept of loyalty and family as Jude Law's Sam is forced to take the throne of Osea. The island destroys him psychologically, preying on his mental demons and the loss of his son, Nathan. However, justice is seemingly served at the end of Season 1 when he's remains on Osea as some sort of penance, while his estranged wife, Helen, and daughters, Lu and Ellie, make it back to the mainland.
The ending of The Third Day Season 1 creates a few intriguing avenues for a second season, as there are many on Osea who might want to silence Sam's family and keep the sanctity of the pagan island intact.
Jess as The Mother
The Third Day Season 2 can further explore the wicked Jess and her daughter with Sam, Epona, as these women aim to change the way Osea operates. Jess believes a "Mother" should run the island and wants her daughter to be this messiah. If Sam's family leaves the island alone, the show could focus more on domestic relationship between Sam and Jess, who hates him with a passion.
Jess doesn't want Sam near Epona, fearing he might corrupt her. Plus, seeing the patriarchy removed from Osea could bring about a new religion and rituals. Human sacrifices made Season 1 intriguing, so Jess, who belonged to another cult, could further develop this aspect of the series. Given that her mysterious husband wanted to find her and their two daughters, Jess is in danger, which may see Osea become darker than ever to ensure intruders don't endanger it again.
Purging The Outsiders
Chances are Jess doesn't want to risk anyone revealing the truth about Osea, so she could send agents out to hunt Helen and the girls. That being said, Helen might not have survived the hypothermia she was experiencing as Season 1 ended, meaning Ellie and Lu could be very vulnerable. This might even tempt Sam to leave the island to save them if he knows Jess has a hit out on them.
It wouldn't be hard for Jess to go after Sam's family, as Osea has many agents out in the real world. Previously, they kept track of Sam's family and were able to kidnap Nathan, so it wouldn't be surprising if Jess can get people on the mainland to go after the ladies to ensure her rule stays intact and Epona's empire remains untouched.
Destroying Osea For Good
Usually, people come to Osea to get something and leave, but no one ever wants to burn it down. However, whether or not Helen dies, Lu and Ellie might reveal the truth about the island, as as they think Nathan is still alive, though in reality it's just another kid related to Sam. Still, it's possible an undercover cop or two might come for evidence of the coup and bloodbath from the series' first episode.
Osea is great at cover-ups, so it'll have to be very sneaky, especially after Jess' coup cost so many lives. This could create a rescue mission for Sam as well should he want out. What would complicate things is while he may not care for Jess, Epona is his, not to mention fake Nathan does have real Nathan's memories. So Sam's real test may be about whether he wants to raze his kingdom and bloody family legacy or let it to survive, as it's still home to his kin.
HBO's The Third Day stars Jude Law, Naomie Harris, Katherine Waterston, Nico Parker, Charlotte Gairdner-Mihell, Paddy Considine and Emily Watson.