Plot

When Detective Mike Hoolihan is called to investigate the shooting of leading astrophysicist and black hole expert, Jennifer Rockwell, she is affected in ways she struggles to comprehend.

Detective Mike Hoolihan (Patricia Clarkson) is investigating the murder of Jennifer Rockwell (Mamie Gummer), an astrophysicist at an observatory in New Orleans. She had presented a talk on black holes & dark matter (which comprises of 90% of the matter in the Universe and is yet undetectable) in the evening but was found dead in the morning by the manager of the observatory Ian (Toby Jones). She had been shot in the face, but there was no weapon. There is a sock, and a jar of moisturizing cream found at the scene. But a few items like Jennifer's scarf that she was wearing at the time of her presentation are missing. Ian claims that he was with his associate Sabrina (Bri Collins) all night. Ian says that the roof of the observatory was open when he found Jennifer's body, and it was raining, so the first thing he did was to cover the telescope, else it would have been ruined.

The sock is traced to Jennifer's boyfriend Duncan (Jonathan majors) who claims he left hurriedly to work on a new theory. Duncan was working on the theory of Multiverses and did not know that Jennifer was found dead that morning. Duncan is supportive of Mike in the beginning but starts asking for a lawyer as her questioning gets more intense. Mike believes that both Ian and Duncan are lying. Jennifer came from a celebrated family. Her dad was a Vietnam vet and her mother an awarded Astrophysicist, while her 2 brothers Walt and Bray ran a successful electronics company. Her mother Miriam recently received a Woman of Substance award for her humanitarian and charity work.

Mike is an alcoholic and has come through a series of foster homes. She remembers nothing about her childhood. Jennifer's father Tom comes by to the police station and wants to be given access to suspect Duncan. Mike refuses and says that the killer will be brought to justice. Jennifer's autopsy reveals traces of semen, but no traces of moisturizing cream. A red scarf is missing from the scene of the crime.

Jennifer's home is full of Tchotchkes and other old nick-knacks but strangely has no photos of her family members. Mike passes out when she picks up a Florida Snow Globe and imagines unique blue marbles similar to one that is on a string around her neck. When she comes to, she talks about the marble, and how she doesn't remember where it came from. She was an orphan and has always had it. Her co-investigator and supervisor suggest that this looks like "The .38 Caliber Killer", who killed young women, but hadn't struck in many years. The murderer always exchanged nick-knacks with his victims and stuffed a sock in their mouth, so they could not scream. The victim's face was blown right off. Mike reckons that the killer was in his 20's during his first killing spree many years ago and has now resurfaced for some reason.

While doing a more detailed search of the area, Mike finds a gun in a case, and a red scarf she had been having dreams about. The gun, a .38 revolver, is traced to the observatory manager Ian, who admits he found it, and tried to dispose of it so he wouldn't be a suspect. Figuring from where the gun originally lay, Mike concludes that Jennifer had shot herself. The investigators agree since one of the bullets also had Jenifer's fingerprints on it.

In photos of the crime scene, Mike realizes that there are no photos of the jar of moisturizing cream that she noted. When she buys a jar of the cream, she reacts as if memories come flooding back. A video made during Jennifer's presentation on black holes shows some of the people who attended. There is a shadow of a man with a hat - very much like Jennifer's fathers. Mike checks out the family home, and Jennifer's 2 brothers. She finds an old brooch that Jennifer had been wearing but was missing from the murder scene.

As she speaks with the family members, it becomes clear that Jennifer's father Tom (James Caan) is an intimidating figure, and other family members (wife Miriam (Maime Gummer) and 2 sons) are afraid of saying much around him. Mike notices that an object from one of the .38 Caliber Killings is in a picture of the family. A witness from one of the old murders' recounts hearing the suspect walking as if he had a cane, just like Jennifer's father. In photos of the father, he seems to switch the cane from his right to his left hand, using it inconsistently.

It appears that the father had been killing young women who looked like his mother, but the killing had stopped when his daughter (Jennifer) was born. Mike goes to a gun shop and buys a .38 revolver. She confronts Jennifer's father, but he grabs the gun from her and talks her out of her suspicions. She returns to the observatory, and considers suicide, but instead checks out an old, boarded up house. She now knows that Tom is the .38 caliber murderer, and his family knew this dark secret, but was afraid to speak because of Tom's fear. So, Jennifer took the only path of escape available to her as she could not bear that her dad brought her nick-knacks from all his murder victims as some sort of sick fetish.

In the house, she relives the murder of her mother. She was hiding in a closet when the .38 Caliber Killer shot her. Young Mike came out of the closet and rubbed the moisturizing cream on her dead mother's hands, asking her to wake up. Blue marbles had spilled all over the floor, and young Mike carries one out as she leaves with a police officer. The killer had taken the Florida snow globe. Mike gets into her car, and drives away, knowing that she has solved the mystery of Jennifer's death, the .38 Caliber Killer, and her own demons.