Danville nearly tied it three minutes later when Tanner Perkins headed a perfect corner kick by Daniel Gerber, but it just missed the goal.
Plainfield iced it with six minutes remaining when Connor Cutler took a left-to-right cross from Law in the box and put it in.
Brokamp said Danville’s season, which saw the Warriors go 13-4 and win the Sagamore Conference for the first time in a decade, was memorable throughout.
“I’ll remember this team, especially for the 11 seniors we had,” Brokamp said. “I think a lot of people didn’t expect us to be this good after losing a lot of key players from last year, but these guys stepped up.”
Plainfield (11-5-2) will face Brownsburg at 7 p.m. Wednesday, with a chance to avenge an earlier 2-1 loss to the Bulldogs.
“It was a good match the first time, and I hope to see the same type of competition along with us getting the win on Wednesday,” Knueve said.