As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IMMEDIATELY FOLLOWING TAKEOFF, THE FLIGHT CREW OBSERVED AN ODOROUS VAPOR IN THE CABIN. FOLLOWING CONTACT WITH ATC AND REDUCING CABIN AIR INFLOW, THE CREW IMMEDIATELY RETURNED TO THE DEPARTURE AIRPORT UNEVENTFULLY. THE SMOKE OR VAPOR ACCUMULATION BEGAN DISSIPATING FOLLOWING ENGINE POWER REDUCTION. THIS INFORMATION WILL BE UPDATED AS FURTHER INFORMATION IS ACQUIRED.