The Roommates (1973)

Looking to spend a swinging summer at Lake Arrowhead, Carla, Beth, Brea, Heather, and Heather's cousin Paula head to the picturesque hills for a little R&R... but a pall soon casts over the girls' sunny vacation when a mysterious murderer begins picking off the lake's bevy of beauties. Can the killer be stopped before the coeds' summer fun ends in blood-spattered chaos?