Why does the introduction describe Trifles as a "detective drama...with a twist"?

Because they are just regular wives of farmers and not detectives.

Explanation:

There are several twists to the play "Trifles." The women are not regular detectives that are normally on television. Instead, they are farmer wives. None of the women are psychics, talk to ghosts, write crime blogs/books, or cops.

The woman also do not share any evidence that they find with regular cops. They are not there to give the criminals any justice, they break the cases and go on to the next. They hide all evidence from the cops.

The play was written by Susan Glaspell.