What was found
ALL OF CREW NOTED A MELTING OR BURNING PLASTIC SMELL. WE WERE ABOUT TO BEGIN OUR DESCENT FOR BASE, AND WERE ONLY ABOUT 15 MINUTES OUT, WITH MULTIPLE ALTERNATIVE AIRPORTS BELOW/NEAR US IF THE SMELL GOT WORSE AND I BECAME MORE CONCERNED ABOUT AN IMMINENT CHANCE OF FIRE. I DECIDED CONTINUE TO BASE UNLESS I NOTED ANYTHING OF ADDITIONAL CONCERN, IN WHICH CASE I WOULD DIVERT TO THE NEAREST AIRFIELD. WE LANDED UNEVENTFULLY. AFTER SHUTDOWN, WE TRIED TO IDENTIFY THE SOURCE OF THE SMELL, BUT COULD NOT... OTHER THAN IDENTIFYING THAT THE SMELL WAS STRONGER TOWARD THE FRONT OF THE CABIN, AND NO SMELL WAS APPARENT IN THE ENGINE COMPARTMENT.