Edward is King and Uhtred is no longer persona non grata in Wessex (and certainly is non-non grata to Aethelfraed...). Uhtred receives word that his estate in Northumbria, Bebbanburg, taken over by his uncle Aelfric, is under attack by Scots. Moreover, due to these attacks Aelfric's forces are dwindling. Uhtred sees a chance to reclaim what is rightfully his, ideally with help from King Edward. Meanwhile, an uneasy standoff exists between the Saxons and the Danes in Wessex, Mercia and East Anglia but the Danes have a scheme afoot.
After the brilliant Season 3 I was wondering where the series would go next. For three seasons now I've been wondering when Uhtred will pursue his claim to Bebbanburg. This aspect of his life didn't feature at all in Season 3, making me half-think that he's given up on his claim and revenge on his uncle.
Well, now we have the answer and it sets the plot for the season. He certainly hasn't forgotten about Bebbanburg and his uncle and fully intends to reclaim his title. This sets things up for an intriguing plot loop that is more than three seasons in the making.
In addition we have the usual Saxon-Dane friction down south plus the internal political machinations with (as always) Aethelred and newcomer Aethelhelm to the fore.
So a great setup for what should be another excellent season.
However, on a negative note, there are two large plot implausibilities / inconsistencies. Why do the Saxons continue to trust Haesten when it is very clear that his loyalties lie with the Danes? He's betrayed the Saxons on numerous occasions now, to the point of literally fighting against them.
Similarly, why is Aldhelm still working for Aethelred? You'd think after sometime stabs you and leaves you to die you wouldn't go back to them...
I can see why these dynamics exist, as they help this season's arc, but these do make for a weakness and lack of continuity in the season-on-season plot.