For the target language, you could choose a point that is repeated in the text.
In your example of a train driver getting lost, there might be various examples of the simple past or a variety of past tenses. You might be able to work on the use of the infinitive. For example: he decided to go back, it was impossible to see where he was going. Any of these would provide you with a grammar point to work on.
There could also be a common theme in the text that would allow you to work on vocabulary. For example words related to driving: change gear, go faster, slow down. Words related to directions could be another option. For example, he turned left, he went straight ahead.
You could also choose to work on structures such as "If he hadn't lost the map, he wouldn't have got lost" or "he should have turned right at the signals". This might involve working on language that doesn't appear in the text. In this case, you would need to build up the situation and try to elicit the structure from your students. For example, the questions "why did he get lost?", "Because he took the wrong turning at the signals" could lead you into the structures suggested above.
Once you have decided what your target language will be, you need to decide how to focus students' attention on the language. You will also need activities that will allow students to practise using the language. When you planning the lesson, you also need to consider your students' level and the work they have done previously.
The above are some general ideas for dealing with the text and ideas for areas to consider. I am unable to give you more specific comments without seeing the text and without knowing the students' level.
I wish you good luck on your course. If you have any more questions, please write in again. Please remember to include details about your students such as level or age.