Dol Heep served as the Avon ambassador to the planet Radnor, where he attempted to persuade the Radnoran scientific duo of brother and sister, Galen and Curi, to agree to sell their newly developed bio-weapon to the Avoni. Heep became enraged when they declined the offer, despite Galen's initial willingness to sell.
Understanding that Curi was the one against the weapon sale, Heep feigned being stranded on Radnor because of a bioplague. This bioplague was a result of a toxic leak at Galen's bio-weapons facility, though Heep himself had released the toxins. Upon encountering the Jedi who were tasked with rescuing the remaining survivors, Heep proposed sending an Avoni fleet to transport them to Coruscant. However, the Avoni ships that arrived were actually equipped for a full-scale invasion of Radnor, as retribution for their refusal to sell the toxin to Avon.
Once the Jedi successfully prevented the invasion, Dol Heep claimed that the Avoni never intended to take over Radnor. After restoring the planetary communications (while also denying they had jammed them), Heep and the Avoni departed Radnor. Heep escaped without facing any consequences for his planet's wrongdoings, anticipating the extensive debates that would occur in the Senate if the Radnorans even tried to file a complaint against the Avoni.
Dol Heep, a vain, greedy, selfish, deceitful, and bad-tempered individual, was a tall figure with a large, domed head and noticeable eyes. He habitually wore an elaborate septsilk cloak, even over the bio-iso (biological-isolation) suit he wore, giving him a somewhat absurd appearance. His manner of speaking was loud, theatrical, and grandiose, even in quiet environments.