A Curious Beginning by Deanna Raybourn

After burying her spinster aunt, orphaned Veronica Speedwell is free to resume her world travels in pursuit of scientific inquiry—and the occasional romantic dalliance. As familiar with hunting butterflies as with fending off admirers, Veronica intends to embark upon the journey of a lifetime.

But fate has other plans when Veronica thwarts her own attempted abduction with the help of an enigmatic German baron, who offers her sanctuary in the care of his friend Stoker, a reclusive and bad-tempered natural historian. But before the baron can reveal what he knows of the plot against her, he is found murdered—leaving Veronica and Stoker on the run from an elusive assailant as wary partners in search of the villainous truth.