I'm not a diary thief, I'm a professional investigator
She was going to get the job done even if it killed her.
Which it might.
That was entirely a possibility.
One which she was very much aware of.
But she had to.
She owed it to her husbands. After all, if she died, it was likely whoever was manipulating things would have no need to keep her husbands locked up, and they'd be free to go home and raise Snowball.
That was too sad to think about, though.
She'd instead rather make sure everyone made it out from this frame job safe and sound, without starting any wars or causing Octavian to rashly defect from Pristan for true love.
Or...
Also without her having to find out if Octavian might not do that.
...That was an unsettling thought.
Anyway, she was focusing on finding clues first.
Mostly, though, she wanted to clear the air once and for all.
If the culprit was found guilty, then Isabelle could focus all of her energies into spending time with her men.