Gunilla's ghost keeps telling about her fate. Her loved one Gustav didn't die in a storm and had came back, but then he turned into a zombie! He attacked Gunilla and her adoptive father Athor shot him! It turns out Gustav was killed by his crew at the sea by Athor's orders, and the body was brought to him so he could practice his art of black magic by bringing Gustav back to life. Except as an undead zombie who he can kill before Gunilla's eyes to prove her once and for all that he's gone and she should forget about him. These horrific events then led Gunilla taking her own life by drowning.
Now we know the real story about her fate, but Gunilla's ghost doubts that our heroes really understand her plight and sorrow...

In some versions of the real life ghost story of Gunilla it's told that her lover didn't die at sea and once came to visit her, but then he fell down dead before her, hinting that Gunilla's father/adoptive father killed him and in some version also killed Gunilla. From this I got the idea of her lover turning into a zombie that her adoptive father kills.