Little is known about Russian Olive to Red King except for the fact that the Immonens have been working on it for a long time. Kathryn finished the script sometime in 2010 and Stuart has been drawing it when his work-for-hire schedule allows. The book has been referenced in several interviews over the last few years, including this one at Avoid The Future, where Kathryn described Russian Olive with some specificity:
It's two parallel narratives detailing the final days of a relationship. Red King is the man left at home struggling unsuccessfully with an overdue deadline and the unexplained disappearance of his partner, Russian Olive, who may or may not have survived a plane crash in the northern bush. It's also got petroglyphs and Chekhov. Sounds like a scorcher, right?