As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENROUTE, REAR CREWMEMBER REPORTED A STRONG ODOR OF BURNING PLASTIC, WHICH SUBSEQUENTLY TRAVELLED TO THE COCKPIT. FLIGHT WAS ABORTED AND RETURNED WITHOUT INCIDENT TO DEPARTURE. INSPECTED THE FWD AND MID BELOW PANELS, AND EQUIPMENT SHELF. FOUND NO EVIDENCE OF ANY BURNED WIRES OR PLASTIC. RAN AIRCRAFT FOR 10 MIN AT POWER COULD NOT DUPLICATE THE ODOR. THE AIRCRAFT WAS RETURNED TO SERVICE.