[4] In the opening chapter set in Norway, Gisli Thorkelsson is an uncle and namesake of the saga's title character.
This Gisli avenges his elder brother Ari, defeating a berserker with a sword of assured victory named Grásiða (Grey-blade,[5] Grey-flank,[6] Graysteel[7]).
Gisli kills Bard, and Thorkel incites the dead man's relative Skeggi the Dueller (Hólmgang-Skeggi) to take revenge and stand as suitor for Thordis.
The dueller challenges Kolbjorn who has become Thordis's new preferred suitor, but Gisli fights the duel instead and prevails over Skeggi who has a ringing sword named Gunnlogi (Battle-flame).
[13] While attending a thing (an assembly), the hero's close-knit group learns that a wise man named Gest has predicted discord among them (the "Haukdal men") in three years.
Thorkel reacts to the news more badly than Gisli, and first lashes out at his wife by refusing to let her sleep in the same bed as him, which is immediately quashed by her who threatens him with divorce.
Thorkel will relinquish the land and farm, but will claim movable assets, including the broken heirloom sword Grásiða.
Gisli sends his farmhands to warn Vestein away, entrusting his messengers with a special coin he crafted as a token of dire danger.
The saga states that the custom obligated the person who extracted the murder weapon to carry out vengeance, and Gisli takes the spear (Grásiða).
Gisli sent his foster daughter Gudrid (Geirmund's sister) to Saebol to see what was happening, and discovered that Thorgrim, Thorkel and the rest are fully armed, prepared for a fight.
[b][29][30] In order to avenge the death of Vestein, a man to whom he is bound, Gisli murders Thorgrim and escapes into the night without being discovered.
Aud, Gisli’s wife, remains loyal throughout the saga and refuses to divulge the location of her husband, even when Eyjolf offers her three hundred silver pieces, help in remarriage and reminds her of her current hard life at Geirthjofsfjordhur.
Gisli's dreams of a mysterious woman pouring blood on him continue to plague him, and eventually he is not able to run from his problems or the people who are hunting him.
Aud converts to the Christian faith and with Gunhillda, the widow of Vestein, takes a pilgrimage to Rome, never to return to Iceland.
[32] The longer version explicitly calls Thorkel lazy, and adds he is a dandy preoccupied more with fashionable attire than labor.
[35] Gísla saga served as inspiration for both Maurice Hewlett's novel The Outlaw (1919) and Kári Gíslason's The Sorrow Stone (2022).