In 2379, Donatra was a co-conspirator in a plot to elevate Shinzon to the position of praetor of the Romulan Star Empire, and, along with fellow commander Suran, acted as a military advisor to Shinzon.
When Shinzon expressed skepticism regarding Suran's loyalty, he instructed Donatra to be vigilant regarding Suran's actions, and to eliminate him at the first indication of treachery. Donatra attempted to seduce Shinzon, but was soundly rebuffed by him due to his loathing of all Romulans.
This, along with her discovery that Shinzon was planning to use thalaron radiation to destroy all life on Earth, caused her own loyalty to waver. Later, she held a covert conversation with Suran, questioning whether they truly desired to stand by as Shinzon committed genocide, stating, "His sins will mark us and our children for generations."
Later, along with another warbird, Donatra commanded the Valdore in assisting the USS Enterprise in combat against Shinzon's vessel, the Reman warbird Scimitar. She explained to Captain Picard that the Empire considered Shinzon's coup a matter of "internal security." The Valdore was critically damaged when Shinzon feinted to lure Donatra into close range of the Scimitar then fired at point-blank.
This, along with the disabling of the other warbird, left the Enterprise crew to face the Scimitar alone. After the Enterprise destroyed the Scimitar, Donatra dispatched shuttles with medical personnel and supplies to assist the Enterprise crew in recovering from the battle, and informed Captain Picard that he had earned a friend in the Romulan Empire. (Star Trek Nemesis)
Background information Edit
Donatra was played by Dina Meyer and was named by screenwriter John Logan for his friend Donna Branson, whose name he also used for Branson. (Star Trek: The Next Generation Companion, 3rd ed., p. 354; Star Trek: The Official Starships Collection, issue 31, p. 18)
In the shooting script of Star Trek Nemesis, the first description of Donatra was in comparison to Suran; the screenplay referred to her thus; "Donatra – a key figure in this story so pay close attention to her – is a maturer, beautiful woman... not without a dry sense of humor." 
In the novelization of the film, Donatra's expanded back story is that her father, a prominent Romulan military commander, had "disappeared" (i.e., been abducted and executed in secret) for daring to suggest a less oppressive response to a planetary rebellion to the praetor when Donatra was a young girl. Her mother placed her under the protection and guidance of Suran, who helped advance her career until she achieved the rank of commander at a surprisingly early age.
In novels such as Star Trek: Destiny, Donatra leads the breakaway Imperial Romulan State in opposition to Tal'aura. Rough Beasts of Empire has Donatra arrested during the reunification of the Romulan people under Tal'aura in 2382, falsely accused of being behind an attempt to assassinate Spock, and committing suicide in her cell.
In Star Trek Online, the Romulans reunify in 2385, following Tal'aura's assassination, with Donatra in control of the military and abolishing Reman slavery. She is missing and presumed dead following the supernova of 2387, but she turns up in the "Khitomer Vortex" Special Task Force mission as a Borg drone. She commands an assimilated Scimitar-class ship. After the player destroys her ship, one of the player's bridge officers reports that several escape pods were launched and sent to the time vortex. Donatra was presumably inside one of them and was sent back in time.