A Lesson in Murder has several interlocking stories and several future stars including David Tennant and Danny Dyer.
Foyle manages to deal with the death of a conscientious objector in the prison cells rather rapidly. After being refused exemption by a tribunal judge, his body is later found in the cells, an apparent suicide. Foyle knows from the bruises in his body, wet clothes that some police brutality was involved because of his pacifist views. The pacifist group in the town are not happy especially with the tribunal judge who rarely recognises a conscientious objector.
The judge, Lawrence Gascoigne gets death threats which Foyle investigates. More heartbreaking the judge and his wife as well as their grown up daughter are looking after a little boy, an evacuee from London. At first it seems only the daughter cares for the little boy, Mr Gascoigne and his wife finding him to be a nuisance. However when the boy dies from an explosion you see the pained anguish in Mrs Gascoigne's face as she cries over his murder.
The third story is of the Italian restaurant owner and his son Tony who dates Foyle's driver Samantha. Tony also gets involved with a rebellious old friend. Any of these two as well as someone from the pacifist group could be planning to kill the judge.
A strong mystery, with several splinter plots. Foyle has to tell the father of the little boy what happened to his son. Foyle also investigates why the judge allowed one person conscientious objector status but refused others. The Italian restaurant part was rather predictable, once the bombing starts you can sort of figure it will not end well for the restaurant. However the episode shows that Foyle is a man of integrity with strong beliefs in right and wrong but also reconciles that justice needs to be flexible.