Police tactical units battered down doors across Arbroath in a drugs swoop that secured heroin worth £200,000.
A house in Helen Street was one of nine targeted in a crackdown linked to three addresses in Dundee on Wednesday.
Chief Inspector Gordon Milne, who is leading Operation Shrug, confirmed several packets containing controlled substances had been found.
A specialist team, including officers from Aberdeen and Fife, was drafted in for the day of strikes which began at 9am and lasted into late afternoon.
Mr Milne said the 52-strong unit had been briefed on an Angus-based serious organised crime gang, on whom evidence had been gathered during a previous phase.
Homes in Westhaven Gardens and Ladyloan were also among those raided in Arbroath, while in Dundee, officers entered addresses in Cleghorn Street, Fullerton Street and Brantwood Avenue.
In Angus, three men were detained, with one later arrested. Drugs detection dogs helped carry out searches of five addresses, leading to heroin with an estimated street value of more than £200,000 being recovered in Dundee.
Mr Milne said: “We have been working on Operation Shrug for the last three months and today is the culmination of that hard work.
“I have no tolerance for people who deal in drugs. They are responsible for misery, death and harm within our communities.”
Police have also announced the seizure of £400,000 of cocaine in a separate operation in Dundee on Wednesday.
Three men have been charged and are due in court.