Primer

Four engineers, Aaron, Abe, Robert, and Phillip, lead a dual life by working for a large corporation during the day. At night, they shift gears to run their side business from Aaron's garage, focusing on crafting and selling JTAG cards.

The earnings from their side venture are invested into pet science projects with the ambition of catching the interest of venture capitalists. This endeavor reflects their dreams of innovation and funding.

Tensions arise in the group as they struggle to agree on the next project to pursue. This discord leads Aaron and Abe to separate their efforts, focusing on reducing an object's weight with the hope of groundbreaking results.

Their invention yields unexpected results, dramatically increasing the time reading of a clock left inside the device by approximately 1,300 times. This revelation prompts Abe to conclude that they may have accidentally created a time machine.

Abe secretly constructs a prototype for a larger time machine capable of transporting a person. After testing it by traveling back to earlier that day, he shares his findings with Aaron, sparking further collaboration.

As they develop their time-travel technology, Aaron and Abe choose to exclude Robert and Phillip from their plans. They fabricate a story about needing to fumigate the garage to keep their secrets under wraps.

Using their time machines, Aaron and Abe start to make bold stock market investments, profiting from their manipulation of time. Their excitement grows as they explore the potential of their invention.

The unexpected arrival of Thomas Granger, Abe's girlfriend's father, introduces complications as they seek his financial support. An incident renders Granger comatose, raising serious concerns over the disruption caused by their time travel.

Disturbed by the consequences of their actions, Abe constructs a failsafe machine in secret, intending to go back in time to prevent their initial foray into time travel. This plan showcases his anxiety about the repercussions.

Abe successfully travels back four days, but upon arrival, he collapses from the strain. Once recovered, he discovers Aaron has taken control of the timeline, manipulating events to assert dominance over their time travel project.

In a bid to gain the upper hand, Aaron proposes to recreate past events, particularly a party where an incident involving a crasher aimed at Rachel occurs. He convinces Abe to help change the outcome, complicating their friendship.

Their continued experiments with time travel lead to a breakdown in communication and trust between Aaron and Abe. The strain becomes evident as their health deteriorates under the pressures of their actions.

Aaron begins to suffer from severe health issues, displaying symptoms that resemble a stroke. His struggles with basic tasks further isolate him from Abe, leading to a breakdown in their collaborative efforts.

As tensions escalate, Aaron confronts Abe regarding his possible ulterior motives. In a drastic decision, Abe chooses to remain in the current timeline, aiming to influence his past self and Aaron to abandon their venture.

In the film's closing moments, the earlier version of Aaron is depicted in a phone call indicating financial distress. The film ends on an unsettling note, revealing a situation where one version of Aaron oversees a group starting to construct a massive box.