East by Susan May Warren

She won’t stop chasing the story. He won’t stop chasing her.

Investigative journalist Chloe Silver has proof of something monstrous — a bioweapon being tested on children in the jungles of Myanmar. She’s not leaving without exposing it. She’s not leaving with anyone’s help.
Then operative Easton “Skeet” Blackwood shows up with extraction orders, a protective streak, and a smile that makes her forget to breathe.
She’s not going anywhere.
So he proposes a different play: go undercover as honeymooners to infiltrate the medical conference where the weapon is being sold. Professional. Strategic. Completely fake.
Except the feelings stop being fake somewhere between Thailand and Sicily. And Alan Martin — the terrorist who already wants Chloe dead for being Selah Silver’s twin — is done hunting.

Now he’s setting a trap.

The tropes you love. A race against mass murder.