It contrasts war and peace by describing a bomber against the backdrop of a peaceful setting. (Apex)
Independent clause uses commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.
The first one is an "idiom" / or, "idiomatic expression" ; that is: [to have] "tricks up [one's sleeve's]" .
The second one is "hyperbole" (gross exaggeration).
The third one is "personification" — but also "hyperbole" (gross exaggeration).
__________________________________________________________
I am assuming that you are asking about Mr. Frank. He finds the secret room when he returns at the end of the war.
I THINKKKKKKKKKKKKKKKKKKKK
