The series is now tied at 3-3 after the Tradesmen suffered a 4-1 loss to the Wolfpack on Saturday at the County Arena in Coxheath.
Andrew Martell, Nick McFarlane, Shaun Miller and Alex Arab scored for Cole Harbour, while Dylan Morely had the lone goal for Cape Breton.
Ryan Huestis made 20 saves for the Wolfpack, while Liam MacDonald stopped 31 of the 35 shots he faced.
Cape Breton (13-20-1) entered the playoffs as the sixth placed team, while Cole Harbour (22-11-1) finished third in the regular season in the eight-team loop.
A date for Game 7 has yet to be determined.