It's set in modern Elkhart County, Indiana, and follows the relationship of two sisters working through their own connections to the murder of their mother 20 years earlier.
The two Eberly sisters are the core of the film. Marian (Amy Jean Johnson) has remained on the family farm and married John Miller (Brian Boland). They have a young daughter, Rebecca (Maddie Abshire). Hannah (Joey Honsa) was slightly younger than Marian and left for Chicago to pursue a career in writing. She has left behind her Conservative Mennonite roots, though she has retained an old manual typewriter on which she does all her creative writing. She is unmarried but has a partner of sorts who is only mentioned once.
The next-door neighbor is Isaac Epp (Evgeniy Lazarev) and his son, Ryan (Christopher Collard). Isaac had come from the Soviet Union in the 1960s in hopes of marrying Rachel (Kim Stauffer). Unfortunately, Rachel was already engaged to the man who became Marian and Hannah's father.
Hannah returns to Elkhart County after Rebecca has a severe injury in the field when John starts moving the bailer without realizing Rebecca's presence. Rebecca survives, but her face is seriously damaged.
The film then follows the clash of the sisters' worlds, especially when Marian learns that Hannah is writing a book that includes their mother's murder. Marian wishes that family history remain private; Hannah believes telling the story could be helpful to others. Flashbacks throughout the film slowly reveal more and more about what actually happened the night of the murder and the radically different experiences the two sisters had.
Other issues involve how to pay for Rebecca's treatment since the insurance company won't pay what is needed. Another is how to respond to the impending death in prison of one of the murderers. And finally, what is Hannah to do with her manuscript?
There are some puzzling things about the portrayal of conservative Mennonites in the film. Marian Eberly wears a head covering but seems to be inconsistent in when she wears it. The small Mennonite church they attend uses a hymnal published by Mennonite Church USA, the most liberal Mennonite denomination, which seems unlikely for the context. No pastoral leader appears to be evident either in the church or in the visitation to Rebecca's hospital room or ever visiting the Miller family. The quality of acapella singing is what I would expect in a Conservative Mennonite congregation. Portraying conservative Mennonites that don't use horses and buggies in films is difficult; this movie did a good job. The passive-aggressive silence found in many Mennonites is well represented.
"Pearl Diver" is an interesting film that I think has an unfortunate title. I would have preferred something like "The necklace." Although we discover the source of the "Pearl Diver" title, I don't it really hints at the story.