Plot

A single mistake in the past, by a time travel company in the future, has devastating and unforeseen consequences.

Chicago, 2055. Charles Hatton has made a fortune by founding 'Time safari', which offers rich 'big game hunters' short time travels to kill off dinosaurs just before their natural death. When scientist Travis Ryer notices the weather and wildlife are not behaving as usual, he consults Dr. Sonia Rand, the contractually invisible inventor of the supercomputer which controls time. They soon face 'time waves', each worsening the effects in 2055 of evolutionary distortions, lower lifeforms first. They attempt to identify and rectify the past alteration, but each attempt gets harder in their distorted present.—KGF Vissers

In 2055, a Chicago company specialized in time travel and owned by the powerful and wealthy Charles Hatton organizes safaris for tycoons in the prehistoric era. The team is leaded by Dr. Travis Ryer and the jump is programmed by a computer. However, when something is changed in the past, the time waves affect the present and Travis and his crew, with the support of the inventor of the computer, Sonia Rand, try to find a way to fix the problem.

In the year 2055, the Chicago-based Time Safari company offers the opportunity for the rich people to hunt dinosaurs in the past via time travel technology. As a precaution against the potential change of the past, the company preys only on the dinosaurs who would otherwise die of natural causes and keeps the clients from stepping off the designated path. Because of the dangers of interfering with the time line, the company's activities are vocally criticized by Sonia Rand, the developer of the time machine software "TAMI", who feels disappointed for not receiving credit for her work and is worried that some clients may alter the past through their activities.

A trip with clients Eckels and Middleton goes afoul when the gun brought by team leader Travis Ryer fails to go off. The dinosaur, an Allosaurus, rushes the group, scattering the clients. Ryer is able to kill the dinosaur and afterwards, regroups the clients and returns to 2055 without further harm. However, unbeknownst to the rest of the group, one of the clients had stepped off the path. The next day, however, members of Time Safari including CEO Charles Hatton hear reports of global increases in temperature and humidity, and Ryer observes a sudden increase in plant life.

On their next trip, Ryer and a new group of clients find that the Allosaurus he and the team intend to hunt is already dead and the volcano erupts much sooner. The team quickly returns and reports the changes, causing the government to shut down Time Safari for an investigation. Ryer visits and learns from Rand that Chicago is being struck by "time waves" that cause drastic alterations to the city as they pass due to something that happened on a previous expedition. Ryer and Rand narrowly escape her apartment building after a time wave causes the appearance of thousands of beetles and a tree bursting through its structure. Rand warns them that more time waves can be expected, and each will affect more advanced life forms, humans being the last.

Ryer and Rand return to Time Safari to try to fix what has gone wrong along with the government. Ryer decides to go back in time to undo whatever damages they caused, by ushering their group from the previous trip back to the portal, thus undoing what was changed. He is sent back in time, but instead he arrives in a desert, nearly trampled by some warriors on horseback. He sees another time wave in the past and runs back through the portal to warn the others in the present, that unfortunately that leaves the city without power and now covered by dense vegetation. Evaluating the machine's logs, they find that the Eckels/Middleton expedition had come back a few grams heavier and learn that Hatton and Derris had turned off the bio-filter to save money. Rand reveals that the reason Ryer could not go all the way to the past was because the time waves were creating several walls that blocked any attempt at time travel. They view the recording of that particular trip and are unable to find anything as the recording had a limited range and the two clients were out of view. Rand manages to find a way to use the time machine to go back around the time waves to intercept their past selves so as to prevent whatever happened, but will only have a few seconds to act, and so they have to find out what was changed in the first place to prevent it.

The Time Safari finds their equipment and gear working and in perfect condition, so Ryer and Rand lead a group through the city - now filled with evolved and deadly hybrids and other new hazards that kill some of their party members in order to find Eckels and Middleton. After helping two civilians, they find Eckels is safe but asserts he remained on the path and confirm this after checking his gear and finding nothing out of the ordinary. Eckels tells them where they can find Middleton and where they can get a car to travel there. Eckels tells them that they must make things right and they promise to do so. When they reach Middleton, he is shown to be poisoned by the new wildlife, and commits suicide before they can stop him. Afterwards, they are able to find his gear from the trip and find a single dead butterfly on the sole of the shoe he used for the safari. The party makes it back to Time Safari after more time waves hit, and find Hatton dead and the time machine partially underwater and unusable. Rand obtains the hard drive containing the TAMI software with plans to use it with the nearby university's particle accelerator as a substitute time machine. Derris who had been hiding from gorilla-bat hybrids attempts to join them, but is discovered by the creatures and is presumably killed by them.

With Ryer and Rand as the only two survivors, they finally make it to the university, Rand noted that the appearance of simian-like Babboonlizards from the latest time wave means the next one will wipe away humanity. Rand prepares the accelerator and stays behind while Ryer goes through the time portal, just as the last time wave hits turning Rand into a humanoid catfish-like creature. Ryer catches up to the previous expedition and tells Jenny that the bio-filter was turned off by Hatton and Derris, and that something went very wrong on their previous trip and tells her to give the recording to his past self and only him. He then heads over to Middleton and sees that he's about slip off the path and manages to stop him from stepping on the butterfly before vanishing as the time line has been reset. The expedition returns without incident to the future they had left, Jenny tells Derris that she knows that he and Hatton turned off the bio-filter and to turn it back on. She then speaks to Ryer and tells him that she saw an alternate version of him from the previous time line that was erased. After watching the footage several times, he takes and shares the footage with Rand, and tells her that everything that she warned them about had already happened and the recording proves it. They presumably use it to bring down Time Safari, and make sure nothing like this ever happens again. (Courtesy of Wikipedia)