The Ending Of Four Good Days Explained

A recurring motif in "Four Good Days" is the unfinished puzzle Deb left in the garage, hoping Molly would finish it one day. By the end of the film, four months in the future, we see that Molly has completed it, and the two women sit across from one another to admire it. Then, they mix it up and prepare to rebuild the puzzle all over again.

The completed puzzle symbolizes how Molly is a changed person. In the past, when she was in the depths of heroin addiction, she couldn't finish it, and at the beginning of the film, she even mentions how she hates the puzzle. In the final scene, it's clear she's turned a corner, and while she's still susceptible to her addiction, it appears as though she's made a genuine effort to turn a new page. 

Even the disassembling of the puzzle is significant. Previously, Molly was tasked with completing the puzzle all on her own. This time, when they begin to rebuild the puzzle, Deb is sitting at the table, going through pieces, too. Molly may delve into the depths of drug addiction once again, but this time, she's going to have her mother by her side, helping her put the pieces of her life back together.