Force of Nature by Jane Harper (2018) Pan MacMillan Australia 

Five women go on a team building hike in the Australian bush - only four return.

Federal Police Agent, Aaron Falk wants to find her because she is the whistleblower on a case he is building against the company where she works.

The story's tension is built through the landscape and the discordant personalities of the women.

Will searchers find the woman?  Did one of her coworkers do something to her?  Did she really leave on her own?

The story is dark in a dreary environment.  Like Harper's book, The Dry, Falk has his own demons to deal with while he methodically goes about solving the case.