It's been eight months since the accidental death of Howie (AARON ECKHART) and Becca Corbett's (NICOLE KIDMAN) 4-year-old son. They're attending grief counseling meetings along with the likes of Gabby (SANDRA OH) and her husband, but Howie gets more out of those group encounters than does Becca.
It certainly doesn't help that her sister, Izzy (TAMMY BLANCHARD), is expecting a baby by her musician boyfriend, Auggie (GIANCARLO ESPOSITO), or that their mom, Nat (DIANNE WIEST), keeps comparing the heroin overdose loss of her adult son -- their brother -- to Becca's boy.
Meanwhile, she's been putting away her son's belongings as the memories are too painful, which clashes with Howie's desire to maintain reminders of their boy, all of which results in them clashing in their mutual grief. As a result, he starts to see more of a kindred spirit in Gabby, while Becca starts meeting Jason (MILES TELLER), the high school student who accidentally ran over her son those fateful months ago.
With their marriage progressively crumbling, the couple must decide whether they can make things work or if it's just going to be too painful to go on together.