Sender Films has had a regular presence at Mountainfilm over the last several years with King Lines (2008), Alone on the Wall (2010) and Sketchy Andy (2012). Now, Sender principals Peter Mortimer and Nick Rosen turn their attention to the epic history of climbing in Yosemite, screening a rough cut of Valley Uprising that shows how a ragtag bunch of dirtbag climbers helped change the threshold of what was humanly possible.