The mystery surrounding Mary Alice and her family was the main storyline in the first season of the series, and it is resolved in the first - season finale. Cherry had wanted there to be a "definite end '' to the mystery, hoping to avoid similar viewer fatigue that Twin Peaks suffered after drawing out its central mystery past its first season. ABC executives initially protested the writers ' decision to have Mary Alice purposefully kill Deirdre Taylor (Jolie Jenkins), the woman whose child she had illegally purchased, prompting the writers to make Deirdre violent in order to justify Mary Alice 's actions. Although Mary Alice and her family do not have much of a leading storyline thereafter, the mystery surrounding the character 's suicide in the inaugural season is said to have informed and influenced every other season of the series. In 2006, when asked during an interview what viewers could expect from Mary Alice for the series ' third season, Strong said that the character was "going to be back with an attitude '', stating: "She will be a little less surreal, ethereal and a little more sassy, which means the show is going to be sassier. '' During the series ' final season in 2011, the actress appears as Mary Alice 's ghost to her suicidal friend Bree (Marcia Cross). Strong enjoyed filming that particular scene, as it was the only scene during the entire series that featured solely Mary Alice and Bree. She described the scene as one of her personal favorites and called it an "extraordinary opportunity '', saying: "In a way, Mary Alice becomes (Bree 's) conscious and her guide and her muse in knowing what to do with her life. And it was an exquisitely written scene and it was really, I think in my experience on the show, one of my favorite scenes I have ever shot. ''
when do you find out why mary alice kill herself
the first - season finale