In It for the Monet

In It for the Monet begins with parents who think they have lost their daughter. Mr and Mrs Sheridan ask Ken to find out why Isobel, an art-history student, has changed, and why she suddenly seems to have a great deal of money. Her former boyfriend tells Ken that she gave up rowing a year ago and has a new set of friends.

Laura and Rocky go undercover as students. They see Isobel and her friend Dominique all dressed up and getting into a flashy new convertible, and follow them to a hotel. Rocky sees the two women leave a bedroom after a short time while an Italian man hands over money, and jumps to the obvious conclusion. Laura, outside Isobel's room, finds syringes and a note mentioning poppies and wonders if she is dealing drugs. Ken has to decide what to tell her parents.

The truth is more ordinary. Isobel is selling essays to weaker students, and her tutor, Dr Michael Harrison, knows. Ken is not satisfied, and on a closer look he finds that Harrison has been selling her work around the world without her knowledge, and without paying her. Isobel has just won a doctorate at Florence.

At the end-of-term party Ken tells her what Harrison has been doing. She is furious but cannot expose him, because he could reveal that she has been selling essays herself. In her acceptance speech she hints that other people have been able to benefit from her work, and she asks Ken to hold on to the evidence in case Harrison tries the same trick again.

Harry's story is a farce. Two brothers, Andrew and Graham Barker, are squabbling over a classic car; each says the other stole part of it. Their mother says that, under their father's will, a car that cannot be shared reverts to her, and she offers Ken and Harry £500 to bring it back. They take the body from Graham's workshop while Mrs Barker and her butler provide a diversion, and drive off with the chassis, the brothers in pursuit.

Mrs Barker brings them all to a motorway junction where she and her butler, William, announce that they have just got married and are leaving on honeymoon in the car. She never pays the £500.

Peter Mann wrote the episode and John Woods directs. Clare Holman plays Isobel, Patrick Malahide plays Harrison, and Rachel Kempson plays the mother.

The case is well constructed because both of the false trails, prostitution and drugs, are what Rocky and Laura would find if they started from the assumption that a rich student must be up to something, and the audience is invited to start from the same place. It is also the highest-rated episode of the fourth series with IMDb users.

The weakness is the lack of any penalty for Harrison. Ken's evidence is kept in a drawer, Isobel's speech is a hint, and the man who stole her work is left in post. The Barker farce is a cheerful makeweight, with the unpaid £500 as its running joke.