So evil my love

The doctor's diagnosis was quite correct. Martin Rue died horribly of poisoning, the classic "woman's crime." In this harrowing suspense story there is no uncertainly about the culprit. Olivia Sacret, pious widow of a missionary, has fallen under the baneful influence of a man for whom she will do anything to obtain money. Blackmail was her own idea, but the poisoning, suicide, and hair-raising end of this rapid tale all spring from a love that was murderously evil.

from Goodreads