Since it started in 1968, the BBC Education series Scene has gained a deserved reputationfor thought-provoking problem dramas, sometimes controversial, usually well-written and with a notably good cast. The aim is to use the plays to look at social, personal and political issues and to provoke discussion among the teenage audience.

The difficulty, as with all problem plays, is that the issues may tend to predominate: the situations seem contrived to illustrate particular points, the characters too obviously represent particular attitudes and the dialogue sounds stilted because it has to express not their personalities but their views.

Dear Nobody largely, but not entirely, avoids these pitfalls. It started as a novel by Berlie Doherty, became a play and has now been adapted for this series by Richard Cameron.

The theme is teenage pregnancy, and the dilemmas that arise from it: will Helen keep the child or have it aborted? Does she want to stay with Chris (the father) and perhaps marry him? How will their parents react? What will happen to the careers they have planned? The use of drama allows the moral dimension of these questions to be dealt with in its complexity, rather than as a simple matter of “should” or “shouldn’t”. The two main parts are played by Katie Blake, an attractive newcomer, and Sean Maguire (a former EastEnders star), who give a fine sense of two happy-go-lucky Sheffield teenagers unwillingly “catapaulted into the world of grown-ups”, as they say, when a revision session for exams at her home turns into something else and she finds that she is expecting a child.

Among the supporting characters are a parent who decided to have a baby aborted, and another who, for a long time lost touch with her son. Both might as well come with the word “discuss” printed on their foreheads.

If the reactions of some of the characters are predictable, so too are many of the situations that Helen and Chris have to face. There are agonising difficulties in communication: not only breaking the news to Helen’s parents but even talking to one another on the telephone when younger siblings are listening. There may be no definite “shoulds” and “shouldn’ts”, but in some cases we are given clear examples of positive and negative behaviour by family and friends. Helen’s father (Peter Davison) reacts unhelpfully, while her grandfather (John Cater) proves a tower of strength. Most members of the older generation, we learn, have mistakes in their own past to hide - which may be the most accurate observation in the whole drama.

The most original idea in Dear Nobody is the device that gives it its title: Helen is imagined to have been writing a series of letters to her unborn child, describing her feelings about what has happened. This allows the script not only to explore her emotions in ways that would seem implausible if she were to express them in conversation (or dramatic monologue), but also to achieve a lyrical dimension that contrasts effectively with the mundane remarks the characters exchange among themselves. “Is it you or is it my fear that puts a tiny skipping heartbeat inside my own?” Helen asks her “Dear Nobody” when she first has confirmation of its existence.

The first episode ended with her decision to have an abortion; the second, after she has decided to keep the child, with her rejection of Chris. It is not yet clear whether she decides against staying with him for her own sake or his. The ending (in this week’s final episode) is moving, plausible and unsentimental. It tells us that while some things are irrevocable, nothing is final. Life goes on and the questions for discussion have no “right” answers, only some better and others that are not so good.