Kara sold the food to developing planets, although the product was created by Davros. She planned to destroy Davros so that he would no longer get in the way.
Kara employed Orcini, a Knight of the Grand Order of Oberon, to assassinate Davros, a task which (given Davros' reputation) Orcini considered honourable. She gave Orcini a bomb, disguised as a communications device, which he would use as soon as he had killed Davros. Unknown to Orcini, the bomb would explode and blow up Orcini, Davros, Bostock (Orcini's squire) and whoever else got in the way, as soon as he keyed in the correct code.
When Orcini and Bostock entered the crypts of Tranquil Repose to look for Davros, they encountered one of Davros' Daleks and destroyed it. This alerted Davros and fueled his suspicion of Kara. Davros, suspecting the assassination attempt, contacted Kara to suggest that she "protect" herself with a squad of Daleks. Because she knew it would have given away her treachery to refuse, Kara reluctantly agreed. When the Daleks arrived, they exterminated Vogel and took Kara. Upon entering Davros' lair, she was asked about the transmitter given to Orcini. She denied that she gave him the device, leading Davros to give the box to Orcini and asking him to do what he was supposed to with it. Kara stopped him and admitted the truth. Angered at her betrayal, Orcini revealed a knife and stabbed her. (TV: Revelation of the Daleks)