Isa is a writer for hire, the author of biographical style books that never see the light of day. Just as she decides to give up this work, Francisco appears. He's someone following a dream, to regain a past love that continues to torment him, with confused reasons for hiring Isa's services. Isa soon discovers that her final client has painful and incomprehensible wounds and that he has placed all his hopes of recovery in her, convinced that she has the curative powers that he needs. Francisco's secret will lead Isa to confront her own past and she will eventually manage to save him through her writing. 'Cenizas en la boca' ('A Mouthful of Ashes') could be the most personal and moving work by the author of 'El círculo de Juanelo' ('Juanelo's Circle'). A literary return to his beloved Toledo and a reflection on friendship, love and memory.