It is 1984, and the murder of 15 year old schoolgirl Lynda Mann is all over the Leicestershire news.

Her parents are making painfully heartfelt pleas for anybody with information to come forward. The police are convinced the murderer is local to the area – and that he will strike again.

Their fears are confirmed when the body of a second teenager, Dawn Ashworth, is discovered. Meanwhile, scientist Alec Jeffreys has just unearthed a way to read an individual’s DNA, and is approached by the police to help in their enquiries. These are the true events upon which ITV’s new two-part drama is based.

Code of a Killer has its strong points. John Simm lends an endearing likeability as the haphazard Jeffreys, though it must be said that the script lets him down on occasion. There is a tendency towards predictability – we’ve seen those cliché ‘mad scientist’ characters who run about all over the place, so absorbed in their work that they forget everything and everyone around them, time and time again.

This is never more apparent than in the scene in which Jeffreys’ wife Sue (Anna Madeley) reminds him of his promise to attend their daughter’s school play, only to inform him that the play was that afternoon, and he has missed it. ‘You promised her’, Sue tells Alec, and for all Simm and Madeley’s proficiency, it still feels like a scene which we have all watched many times before.

This predictability causes some friction with regards to the overall plot: we already know what is going to happen, whether or not we are properly clued up on the real events the programme is based upon. Science and police are going to work together, and after a red herring or two DNA is going to solve the crime. It’s an issue which would have been faced regardless, but the occasionally clunky script does tend to emphasise it.

However, the casting is very good. Aside from the aforementioned Simm and Madeley, David Threlfall (Shameless, The Ark) is excellent as DCS David Baker, the detective trying to piece together the murder enquiry, and mention must be made of Hannah Walters and Dorothy Atkinson as Lynda and Dawn’s mothers, respectively; their anguish and grief at the loss of their daughters is painfully real and difficult to watch.

It takes a while to get going and it tends to trip over itself from time to time, but Code of a Killer is still a watchable and enjoyable crime drama. This opening episode ends on the sinister note of the killer still at large, which is a good set-up for next week’s concluding instalment.

Aired at 9pm on Monday 6 April 2015 on ITV.

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