As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, CAPTAIN NOTIFIED CREW THAT SMOKE DETECTORS WERE INOPERATIVE. FLIGHT ATTENDANTS LATER SMELLED ODOR IN AFT GALLEY & SAW FOG AT ROW 20. CAPTAIN ELECTED TO RETURNED DUE TO AFT CARGO COMPARTMENT SMOKE DETECTOR FAULT, FUMES & FOG. R & R AFT CARGO COMPARTMENT SMOKE DETECTOR IAW AMM 26-16-15-400-001-A. GOOD OPERATIONAL CHECK.