Love, vengeance, deceit, war. Basque "terrorists" / "freedom fighters" versus Spanish establishmentarians who are also rather rude. Some (Roman Catholic) religion thrown in, but earthy feelings prevail generally over pious leanings.
May also be regarded as a historical novel, albeit with lots of embellishments.
Dated 1988, it starts with a Hemingway quotation, lauding the Spanish civil war dead. Not a book for the faint-hearted. If you don't like sex, don't read it.