dug in her heels

Miyuki MiyabeのCrossfireを読んでいます。
Chikako smiled brightly, doing her utmost to stay in cheerful, chatty matron mode. "Yes, you did. But since I'm lucky enough to be here now and have the chance to meet Ms. Eguchi, who's in charge of taking care of everything here, I'd like to hear about them from her directly."
Michiko dug in her heels. "The most recent fire did not take place here. It occurred in the school classroom."

"dug in her heels" はこれまでに2度（7/5/2013、6/30/2014）取り上げましたが、意味が直ぐに出てこないので復習です。
・Oxford Dictionary: Resist stubbornly; refuse to give in.: he has dug in his heels and refuses to leave
・Farlex Dictionary of Idioms: To cling stubbornly to one's beliefs or wishes. Please let me tell my side of the story before you dig in your heels on this, OK?

"heel" を含む慣用句は沢山あり、これまでに取り上げた慣用句を下記に示します。
"on the heels of": https://blog.goo.ne.jp/k_akabane/e/345ca5b53905c7ea1cd3ed3d47671429
"heel in": https://blog.goo.ne.jp/k_akabane/e/ffe39f7b5b2396fbe5650ab5de5bde45
"head over heels": https://blog.goo.ne.jp/k_akabane/e/0f44bd52b6ff413abbcdb32619627ecf