I found a novel on my Kindle (喜欢你，我也是) which seem like a teenage romance, and seems fairly readable and interesting. I'm at the start, and thus far Zhang Kankan 张侃侃 and seems to have been tricked into a blind date with Tan Jin (thinking she's there to 补习); they're both teachers. Currently, Tan Jin seems to be confusing her.
It has the line:
I don't understand the part in bold. (It seems Tan Jin is also confusing me.)
"Oh?" Tan Jin suddenly (?) [倏忽之间] hooked the corners of his mouth (?) [勾了下嘴角], "Bankroller makes you do something, you do it, is this the meaning?"
Question: What does 谈晋倏忽之间勾了下嘴角 mean?