Dramatic irony

According to Enciclopaedia Britannica, dramatic irony is defined as “ a literary device by which the audience’s or reader’s understanding of events or individuals in a work surpasses that of its characters.” (http://www.britannica.com/art/dramatic-irony)

In chapter 3 of Spies,  dramatic irony occurs when Keith and Stephen discover the x´s and the !´s in Mrs. Hayward´s diary. These events are described by young Stephen, who has the innocence of a little kid, but we -readers- understand their findings in a different way because we have more knowledge and experience.

The x´s appear in Mrs. Hayward's´diary once a month, some months 2 days earlier or later than others. We realise immediately what meaning the x´s have: they mark Keith´s mother´s menstrual period. However, Keith and Stephen have no knowledge of this so they relate them to their belief that Keith´s mother was a German spy. They conclude that the x´s record her meetings with the Germans. Besides, her menstrual period coincide with the nights of no moon: "Yes, the x´s are approximately keeping step with the lunar calendar. Each month the x is close to the same sign, the full black circle. The night of no moon". So the children infer that dark nights are ideal for these meetings.

After working on the hypothesis about the meaning of the x´s, the children find the little exclamation marks: "The exclamation marks however, happened only 3 times so far this year, and at irregular intervals- on a Saturday in January, on another Saturday in March and on a Tuesday in April. These last date, I´m somehow disturbed to see, is also marked "wedding anniv.""  Keith and Stephen are not able to build up any consistent  theory about  these exclamation marks, but we assume that they keep track of Mr. Hayward and Mrs. Hayward's´sexual activity, which was important in case of pregnancy.

To conclude, there is a gap between our deductions and Stephen and Keith´s due to the character's lack of information about sexual matters. That explains why it is possible to speak about dramatic irony in this chapter.