TV Drama: Beneath the Water

Phillipa Knoxx is a 35 year old woman living in St. Albans. She works for the Hertfordshire Constabulary as a detective in the C.I.D (Criminal Investigation Department0. Unknowingly, she has undiagnosed dissociative identity disorder, which leads her to have a second personality that she is oblivious to. In the scenes prior to the title sequence, we see her drowning a small girl around the age of the audience, but unaware to the audience. We then get introduced to her character as a detective and a new face, Emily Leonard, who we later learn shares a house with Phillipa.
A few days later there is a search for a missing young girl, and we see Phillipa alone, looking around a public lake. She is searching whilst out of hours, which gives the audience an insight of how dedicated she is to her job.
Around 9pm, she is approached by a 15 year old boy who informs her that she's found the body. She follows him closer towards the lake, when we start seeing flashbacks of her drowning the girl. Panicked, Phillipa attacks the unsuspecting boy and drowns him. Although it is more of a struggle, as he is stronger and older, but manages to kill him and returns home dripping wet.
On the 5th day of the search for the girl, news is broadcasted saying that two bodies have been discovered in the lake, and unaware that it was her own doing, Phillipa starts to find the person responsible. Slowly she begins to doubt her innocence, as she looks further into the investigation and rules out all the possible suspects.
The following evening, Emily gets suspicious of her actions and accuses Phillipa of having some involvement in the murders.
Disorder and chaos breaks out as they argue about the case and Emily attempts to ring the police. Phillipa then knocks her out and takes her to the boat house where she drowns her. This time however, she is conscious of her actions...