A police van could be seen on a side street with cast members in police uniforms buzzing around the streets.
The third series of the Sally Wainwright drama will be its last and is set to film across Calderdale and West Yorkshire over the next few months.
The previous two series have focused mainly on the Calder Valley with Sowerby Bridge and Hebden Bridge playing a key role.
According to a synopsis the series will be as follows: "When Catherine discovers the remains of a gangland murder victim in a drained reservoir it sparks a chain of events that unwittingly leads her straight back to Tommy Lee Royce.
"Her grandson Ryan is now sixteen and still living with Catherine, but he has ideas of his own about what kind of relationship he wants to have with the man Catherine refuses to acknowledge as his father. Still battling the seemingly never-ending problem of drugs in the valley and those who supply them, Catherine is on the cusp of retirement."