Carly Wlad and Abagael Thiessen scored in regulation for the Chiefs (2-2-1-0).
Tamara McVannel and Emily Upgang supplied the offence for the Capitals (2-1-0-2).
Red Deer's Sarah Murray made 20 saves for the win as Kathleen Kosior stopped 16-of-18 shots for Central Plains.
The Chiefs went 0 for 2 on the power play while the Capitals failed to score on four chances with the man advantage.
The win places Red Deer as the third seed heading into Friday's semifinals while Capital Plains finished fourth in group standings.
LADY WOLVES 2 THUNDER 1
Danika Ranger turned away 30 shots as Sudbury edged Edmonton to secure first place in round-robin action.
Karli Schell and Melisa Kingsley each had a goal and an assist for the Lady Wolves (4-1-0-0).
Alison Barnett scored the lone goal for the Thunder (1-3-1-0), who got a 19-save outing from Tracie Kikuchi. Edmonton failed to qualify for the semifinals.
STARS 7 ROCKETS 1
Sophie Shirley had two goals and two assists and Karlee Fetch only had to made 11 saves as Saskatoon toppled Moncton to secure second spot in group play.
Nara Elia and Julia Rongve had a goal and two helpers apiece for the Stars (4-1-0-0) while Danielle Nogier, Courtney Cormack and Jordyn Gerlitz added the others.
Lauren Shaw scored for the Rockets (0-5-0-0), who placed last in preliminary play. Brianne Waterman stopped 29-of-36 shots in defeat.