Fort Saskatchewan will be in another game five Wednesday night.
A penalty in overtime resulted in a Lethbridge Golden Hawks goal and a 2-1 provincial final loss.
Jacob Boucher scored the lone goal for the Rangers on a spectacular individual effort.
Fort Sask out-shot the Golden Hawks for the second game in a row, 38-36.
"We have to do what we did tonight but just bare down on every opportunity that we have," said captain Alex Thacker.
The Rangers were in the exact same situation last round, winning the first two games of the series then dropping the next two.
"We got to improve on getting pucks to the right areas so we can get them back," said defenseman Olen Zellweger.
Game five goes Wednesday night at 6:30 p.m. in Lethbridge.