Jarod Syndergaard scored 25 points and Ryan Brasser added 16 for SOS, which trailed by 10 points early on, but came back to knot it up, sending the game to overtime with a late three-pointer. Adam Paulsen added nine points. Austin Katje scored 34 to lead Unity, hitting 7-14 three-pointers.
Syndergaard tallied a double-double by snagging 11 rebounds, and Brasser pulled down eight.
The Knights advance to the District final against Hinton on Tuesday at LeMars.
The Wolverines finished their season with a fine 14-8 record. The teams had split their two WEC games this season.