Police in Port Elgin arrested two people and seized more than 50 grams of fentanyl after an off-duty Saugeen Shores police officer spotted a suspect.
The officer recognized another police service had an arrest warrant out for the man and called headquarters.
When on-duty officers arrived, they found the man and a woman sitting in a car and arrested the pair.
A search also turned up 53.1 grams of the drug.
"The presence of deadly fentanyl in our community puts many people at risk, from persons suffering addiction to first responders," said Sergeant Andy Evans. "The seizure of 53.1 grams of the drug will have an immediate impact on public health and safety."
A 34-year-old Walkerton man and a 35-year-old Walkerton woman face possession and possession for the purpose of trafficking charges. The man is also charged with failing to comply with a release order, namely possession of drugs without a valid prescription.
The charges have not been proven in court.