1
general::
Also, arrive or come on the scene. Be or arrive where an action or event occurs, as in They won't have a wild party because their parents will be on the scene, or Once Bob arrives on the scene, you can expect fireworks. Alluding to the theatrical scene, where a drama is being played, this phrase has been used more loosely since the early 1700s.
American Heritage Idioms
2
general::
Phrase(s): on the scene
Fig. available or present where something is happening or where something has happened. • The ambulance was on the scene almost immediately. • I wasn’t on the scene when it happened.
McGrawhill's American Idioms And Phrasal Verbs