Rió a través del hilo.

[Stu]

I assume this is a common metaphor passing the thread but I dont see the connection

Rió a través del hilo.

[AngelicaDeAlquezar]

Taken like that, with no context, the sentence doesn't make any sense.
But if you are taking this from "El tiempo escondido", the "hilo" is the telephone line.

[Stu]

Thank you for the response, I will have another look at it.