Just looking at the lyrics I get the feeling the narrator had sexual relations with his sister and got her pregnant... perhaps someone figured out and killed her after the child was born? The line "Mother Is Sister mother loved the white ocean" is in past tense and makes it seem like she's dead. I think the line "with my right hand I catch hold of hands that won't stop trembling" refers to the baby, and he's putting it in the trunk - "Now my child and I are packed in together". After the death of his sister and the shame heaped on him by whomever he just wants to escape from it all.
Just looking at the lyrics I get the feeling the narrator had sexual relations with his sister and got her pregnant... perhaps someone figured out and killed her after the child was born? The line "Mother Is Sister mother loved the white ocean" is in past tense and makes it seem like she's dead. I think the line "with my right hand I catch hold of hands that won't stop trembling" refers to the baby, and he's putting it in the trunk - "Now my child and I are packed in together". After the death of his sister and the shame heaped on him by whomever he just wants to escape from it all.
At least that's my take on it.