Rhonu was a female Betazoid serving in Starfleet in the late 24th century.
By 2384, Rhonu held the rank of Commander and was the first officer of the USS Newton, assigned as part of Project Nexus. When Captain Jean-Luc Picard and the USS EnterpriseE were dispatched to assist in preventing the Holy Order of the Kinshaya from accessing the Nexus, Rhonu greeted the captain and invited him to beam over to speak with Captain Thom Bryant.
The plan to destabilize the Nexus was opposed by several of the civilian scientists on board, including Kolb, who sabotaged the attempt, and in the ensuing disruption the Nexus damaged the Newton. Bryant was killed, leaving Rhonu in command of the Newton. The Enterprise crew uncovered evidence of an Orion spy on the vessel, and after confirming Rhonu nor the other bridge crew were the undercover agent, enacted a plan to capture the infiltrator. After the agent, posing as the Arkarian Een Norgadd, was taken into custody, she used her telepathy to determine the truthfulness of his answers. Rhonu did not recognize the spy, as he had avoided her, knowing she would have sensed his true identity.
Kolb desperately desired to enter the Nexus, and Picard was forced to follow to try to reason with him. Kolb ended up exiting the Nexus and dying on Deneva, altering history such that he was not present on the Newton and therefore was not responsible for the sabotage. Due to this change, Bryant did not die in the altered timeline. Picard exited the Nexus and with his advanced knowledge, warned Bryant and the Newton of a spy aboard; Bryant was initially suspicious, but Rhonu detected that Captain Picard had been through the temporal anomaly a second time, although unwillingly. (TNG eBook: The Stuff of Dreams)