The film begins with Jack and Lily painting a nature mural in Katie's bedroom as she naps. The two debate about her future, and whether she will be a podiatrist or a vegan butcher. This lighthearted conversation proves to be heartbreaking, as the following scenes show the parents grieving Katie's death.

As The Starling progresses, viewers slowly learn more information about Katie's passing, and how her mom and dad are attempting to handle the tragedy in different ways.

While Jack is spending time at a facility with counselors, Lilly remains at the couple's home. When she attempts to move forward by removing her daughter's belongings and by working on a garden, a starling bird starts to interfere.

After a difficult visit with Jack at the facility, Lilly has a conversation at her car with Regina. She gives Lilly a recommendation to see Dr. Larry.

When Lilly meets with Dr. Larry for the first time at his vet clinic, she explains that Katie died from SIDS (Sudden Infant Death Syndrome).

"My daughter, our baby, died just over a year ago now," Lilly tells the former psychiatrist in the movie. "SIDS, that's what they told us."

According to the CDC, SIDS is the "sudden or unexpected" death of a baby under the age of one. The infant generally passes either while asleep, or when in their sleeping area.

The exact cause of SIDS remains unknown.

Though Dr. Larry initially tells Lilly that he can't help her, the two meet again after Jack's wife sustains an injury from a starling. He begins to tell her about the various stages of grief, and he later agrees to talk with her about how to deal with her bird problem.

The two continue to meet to discuss the birds invading her vegetable garden, but Dr. Larry ends up helping Lilly with her grief.