In tales of espionage, you often need to describe someone believing, doubting, or fearing something that had already happened. When the main clause is in a past tense and triggers the subjunctive, an event that occurred before the main action must be in the pluperfect subjunctive (trapassato congiuntivo).
This structural relationship between verbs is called the sequence of tenses (concordanza dei tempi).
Chronological Anteriority in the Past
If your main verb is in a past tense (e.g., pensavo, credevo, temevamo) and expresses uncertainty, thought, or emotion, it triggers the subjunctive in the dependent clause. To show that the dependent action happened prior to the main action, use the pluperfect subjunctive.
The pluperfect subjunctive is formed with the imperfect subjunctive of avere or essere, plus the past participle of the main verb.
Notice how the main verbs (pensavo, dubitavo, speravamo) are in the imperfect tense, and the actions they describe (having revealed, having watched, having intercepted) happened even earlier.
Using Essere
As always with compound tenses, verbs of motion, changes of state, and reflexive verbs take essere as their auxiliary. When using essere, the past participle must agree with the subject in gender and number.
Reflexive verbs like infiltrarsi also require essere:
Uncovering the Plot
The pluperfect subjunctive is essential for putting the pieces of a mystery together. By establishing a past perspective about an even earlier action, you can clearly narrate the timeline of a conspiracy.