Bias for anything written by a Spiritan Father (Congregation of the Holy Spirit), and Pere R. P. Liagre, CSSp is one such priest. Twelve chapters, easy to read. Ang perfect leading up to the Feast of St Therese of Lisieux, the Little Flower. I have also been reading the life of Blessed Daniel Brottier, CSSp, and his works with the orphans of Auteuil. He erected a chapel at the school for St Therese before she had even been canonized. Both of my Grandmothers taught me about St Therese & the Holy Rosary.
An outstanding overview of the spiritual life of Saint Therese and the Little Way which she proposes for all men to sanctity. I highly recommend it as a concise summary of her theology and it gets to the core of why she is regarded as a Doctor of the Church.