A wannabe activist who aspires to join a larger action group gets a job at a mysterious energy company he believes is involved in illegal activities.

What does he want to be active about?  I’m guessing it has something to do with environmental  issues.  But a logline should not leave a reader guessing what the role of the main character is.  So be specific:  “An environmental activist….”

What becomes his objective goal as a result of joining the energy company?   What specifically does he want to uncover,  to expose? “Illegal activities” is too general, can cover a wide range of malfeasance.   In “Erin Brockovich” the protagonist must prove that a plague of illnesses in a community is the result of the energy utility dumping toxic waste into the groundwater.

Sounds like a promising idea!

Just make sure to be more specific in your wording. He needs to have a clear outer goal (want) that is properly described in your logline.

And yes, “environmental activist” sounds better than just “activist”, because it gives the reader a clear vision of the main character and his background.