の線は

as for the possibility of…

→ の
phrase Rare #45,381
as for the possibility of… In some contexts, の線 refers to a theory, possibility, or line of investigation. In other sentences, 線 simply means “line,” so the meaning depends on context.
JA: 事故の線は考えにくい。
EN: An accident seems unlikely.

そっちの線は任せるわ。

I'll leave that angle to you.

— GHOST IN THE SHELL (1995)

窃盗の線は忘れよう

Let's forget about theft as a possibility.

— GHOST IN THE SHELL (1995)

被害者の線はイシカワとアズマ

The victim leads are Ishikawa and Azuma.

— イノセンス (2004)