Martha Beck is a grumpy and overweight woman who reluctantly works her job as a nurse and cares for her already slightly senile mother and her friend Daisy every day. When Daisy signs Martha up with a dating agency, the Spaniard Raymond Fernandez gets in touch and first a pen pal relationship develops, then a relationship. When Fernandez breaks it off, Martha makes sure they get back together by threatening suicide. In the process, however, she learns that Raymond is a marriage swindler and cheat, but by Martha acting as his sister in the future, the couple's livelihood can continue to be secured, especially because Martha turns out to be tricky in blowing up upcoming weddings before the event. The condition of their relationship is that Ray, or Charles as he now calls himself, never sleeps with any of the women. However, when the pregnant Myrtle insists on consummation with Ray, Martha poisons her victim. Killing her victim if necessary soon becomes a habit for the couple from then on, but the suspicion that Ray might be cheating on her continues to drive Martha....