On November 13, 1002, King Æthelred II of orders all Danish immigrants in England killed. The Danish respond by sending troops across the sea, and the Vikings—Danish pirates—serve as the “army’s army.” Askeladd’s crew are right in the middle of this.
When English archers ambush their camp, Thorfinn gets a crash course in mass death, killing, and living with it, taking his first life and letting out a cry of vicious despair that carries through the forest, while Askeladd observes in quiet approval.
The battles with the English continue, and Thorfinn continues to kill and gets better at it, with his enemies continually underestimating him due to his size and youth. Askeladd starts using him as a scout, and he manages to kill two foes who come at him, gaining a second dagger with which he dual-wields henceforth.
While on another scouting mission he takes an arrow to the shoulder and washes up on a branch in a river in East Anglia. A kindly, God-fearing mother and her daughter take him in, clean him up, and feed him. The daughter worries (rightfully) that he’s a Dane, their enemy; but her mom doesn’t think any women or children should be bothered with the quarrels of men.
The mother even combs the fleas and lice from Thorfinn’s unruly hair, with the same comb she used to use on her son, who died of a cold two years ago. An English soldier arrives looking for a pint-sized scout, but the mother covers for Finn.
That night, while the daughter continues to argue with her mother about harboring him, Finn abruptly takes his leave, saying just one word to them in English: Run. He then sets a cottage on the beach aflame; the signal to Askeladd to make his landing.
The mother doesn’t run as Finn urged her; she comes to the beach and sees for herself the boy she nursed back to health and harbored: a rabid killing machine. When Finn spots her among the crowd, tears streaming down her cheeks, guilt momentarily washes across his face, as he remembers his own mother and older sister.
Then the mother is simply gobbled up by the charging viking horde, Finn takes a deep breath, and the guilt is replaced by cold detachment as he too gets lost in the crush, joining his fellow fighters in the latest retaliatory raid on a relatively well-off English village. The comb the mother used on him is trod upon and broken, and perhaps with it any possible chance of Thorfinn turning back from his current, blood-soaked path.