The Ultimate Guide to Writing a Logline

This:

In a story of family guilt and trauma, a timid woman and her successful brother confront their turbulent past and learn to let go.

Is not a logline.

This:

After the death of their last living relative, two estranged siblings find themselves impossibly trapped in their ancestral estate, the house itself refusing to let them leave until they face the literal demons of their past—room by horrifying room.

Is a logline.

Enjoy.