Floki (Gustaf Skarsgård) is in agony. Season 4, episode 3, of “Vikings,” titled “Mercy,” kicks off with the shipbuilder enduring a water torture — a punishment King Ragnar Lothbrok (Travis Fimmel) meted out to his treacherous friend in the Season 4 premiere of the History Channel series. But Floki’s painful bellow transforms into a moan of delight as the next scene reveals Lagertha (Katheryn Winnick) in bed with her fellow earl, Kalf (Ben Robson).

“I love you,” he says to her, claiming that the shieldmaiden is more important to him than power. As Lagertha lovingly strokes his face, he then confesses his dream of one day having children with her, providing Lagertha is still “young enough” to bear them. As if the night couldn’t get any more romantic, Kalf steps away to “take a piss.”

Midstream, Erlender (Edvin Endre) approaches Kalf with some news:

“Bjorn (Alexander Ludwig) has left Kattegat,” he says, revealing that Lagertha’s son is living alone in the snow-covered woods of Norway. The two agree that this will be the “perfect opportunity to assassinate him” — and Kalf has just the guy for the job.

But little do Kalf and Erlender, who gave the Berserker his father’s ring for protection, know that Bjorn is sharpening his battle skills. During Bjorn’s wild journey in the woods, he goes head to head with a bear after learning the ferocious creature has been eating the animals caught in his traps.

With a knife, an ax and a hangover (thanks to the booze he found), Bjorn attacks the creature that’s been stealing his food. The bear gets the first hit, scratching Bjorn’s chest open with a powerful blow. Bjorn's adrenaline begins to rush and he stabs the bear to its death, letting out a victorious yell — one Ragnar can hear from Kattegat. Although Bjorn may have won the battle, he still needs to survive the aftermath of the attack.

And Bjorn isn’t the only one suffering. Both Floki and Helga (Maude Hirst) are in their own, personal hell when Ragnar reveals to his prisoner that his daughter has died. “She caught a fever. There was nothing I could do,” Helga, who is exhausted from capturing the dripping water above Floki’s head, says helplessly. It's enough to bring a man to his knees ... that is, if he weren't tied up with rope.

Back in Paris, Princess Gisla (Morgane Polanski) orders a divorce from her “ignorant savage” of a husband Rollo (Clive Standen). Count Odo (Owen Roe) fears that if the divorce goes through and Rollo leaves, the city of Paris will become vulnerable to another attack from the Northmen.

“We have to stop him from leaving. If he leaves now it will be catastrophic for our attempts to defend this city against his brother,” Odo tells Emperor Charles (Lothaire Bluteau).

To coerce Rollo to stay, Odo and the pagan come to an agreement. Odo promises to find his frustrated, foreign friend a teacher that can help Rollo speak and understand French.

In Wessex, Judith continues to work on her paintings. During one of her classes, she questions the monk teaching her about the recent siege of Paris. Her instructor confirms that it was the infamous Ragnar Lothbrok who attacked the city — pretending to be dead in order to enter the cathedral. Judith (Jennie Jacques) relays the report to King Ecbert (Linus Roache).

“Pretending to be dead! Oh, how like our Ragnar,” the king says, amused.

“[The monk] has no news of our Athelstan (George Blagden),” Judith replies, unaware that their beloved English monk is dead.

But Judith receives the closure she needs when both Ragnar and Ecbert have visions of their departed friend, who has appeared with a message. He tells Ragnar to have mercy while he gives Ecbert the sign of the cross before disappearing.

“I believe Athelstan is dead,” Ecbert says to Judith the following morning. “He appeared to me, here, in this room. He blessed me and made the sign of the cross. But he was silent and his image faded as soon as I saw it, and I knew in my heart that he was dead.”

With tears in her eyes, Judith is forced to welcome home her husband Aethelwulf (Moe Dunford), who has arrived to Wessex with Queen Kwenthrith (Amy Bailey) and Magnus, Ragnar’s son.

"Can't a woman cry when her husband returns from a dangerous place? They are tears of joy, Aethelwulf," she lies. "Tears of joy."

The episode ends with Ragnar heeding Athelstan’s message and bestowing mercy upon his friend by cutting Floki down from the cave.

"Vikings" airs Thursday nights at 10 p.m. EST on the History Channel.