Throughout the second series everyone has said that PC Lizzie Adama is inexperienced. She does not follow orders.
It was intimated by DS Sarah Collins that everyone holds the inexperience card for her as an excuse. It might be she is just not cut out to be a copper.
This is demonstrated in the final episode. Adama rushes into her house where Matthew Brannon is lying in wait. She nearly ends up being killed. Even though Collins told her to run away and that armed police were on their way.
Meanwhile Tania's dead body has been found and music teacher Adrian Stephenson is now the main suspect. Only no one has bothered to find out from the pathologist to find out how she died first and what injuries she received.
They go straight in and arrest Stephenson without game plan. Meanwhile Stephenson has concocted false alibis.
It is not poor writing, it is clumsily handled drama. All for shock twist and turns. There were no surprises at the end but a set up for the third series wasl already in play.