Phyllis and Sharon are fighting on a cliff, Dru tries to intervene, and Dru and Sharon end up falling off of the cliff. Sharon is determined dead from hypothermia. As for Dru, her status changes when the mission is switched from search and rescue to search and recovery.
I highly doubt, though, that Sharon is dead. I think this will be how they get rid of Dru but maybe also how they get Sharon to have the upper hand on Phyllis??
Also, maybe Nick will finally realize how much he still loves Sharon if she goes missing for awhile and is pressumed dead for a bit AND that it was Phyllis' fault!