“Afectada por la trágica muerte de su hijo, busca sanar su mente en el pueblo de su infancia, para descubrir que ella no es la única visita inesperada.”

Intriguing.
Strengthen the inciting incident “Affected” is too mild for this event – what about Devasted? You could use “Devastated by the tragic death of her son, …”.

This is what I can see so far.
“Devastated by the tragic death of her son a fractured mother returns to the safety of her hometown, but…”

The “unexpected visitor” line is just a teaser; the reader cannot attain anything from that. If you inform who this visitor is and their relationship with your protag mother, I or the community can take a crack at completing it.

Take care.