Mystery story for learners of Portuguese as a Foreign Language needs main illustration

Portuguese Lab

The Portuguese Lab teaches Portuguese as a Second Language online. It includes podcast, Youtube channel, online courses and e-books.
The target audience: Portuguese learners from all around the world, age 35-65, like interesting and motivating materials that allow them to learn by themselves.

I need an illustration for an online course. The course is for those learning Portuguese as a Second Language and are beginners. The online course includes videos, audio files and PDF documents. I need an illustration because the course is based on the storytelling method. This means the students learn the language through a story.

This is the story summary:
A young woman (30, dark hair) photographer gets involved in the theft of a rare Russian doll from a museum (that has a big emerald on the chest, which makes it very valuable), when she (unknowingly) takes a photograph of the thieves arranging the exchange of the doll for money. She eventually tries to recover the doll in the tunnels of a palace in Sintra (a village close to Lisbon).

What I imagine:
When I imagine the illustration I see the main character (young woman) running out of a tunnel holding the rare doll in her hand, being followed by a figure of a man in the dark (silhouette, since the identity of that person is unknown).
Maybe she can be slightly turning around looking at the silhouette in the dark (so that we are also drawn in that direction after).
If possible, the exterior (garden/palace) should be visible (even if just part of it).
I would also like for the emerald to be visible (treasure aspect).
This scene happens at the end of the day, when it's beginning to get dark. Maybe just a hint of sunset, for example, so that the image is not too dark.

In terms of style, minimalistic or detailed, I am really open to suggestions. It doesn't need to be really realistic, but if it is minimalistic I wouldn't want it to look as something for kids (the target is a bit older, 35-65).

The main character is a woman, circa 30 years old, medium height, brown hair. I would like it for her to be wearing something informal, like jeans and t-shirt or simple blouse, and maybe a simple jacket.

I would like the illustration to transmit mystery, but also be full of movement and color (not too gloomy).
I like color, and it would be nice if the eyes are drawn to the main character and the doll, standing out from the background (that is probably darker, since she's coming out of a tunnel).

This illustration will be visible on the sales page of the digital course and other materials (covers, etc.).
Preferably a horizontal image.

Here are some photos of the real palace in Sintra where the action takes place (Quinta da Regaleira). Also some images of russian dolls.