From The Perry Mason TV Show Book
Inventor Walter Randall wants a divorce. His icy wife Laura says no. Walter is in love with Laura's secretary, Phyllis Hudson. Laura gets back at Walter by blackmailing her embezzling accountant into building a time bomb that will destroy Walter's underwater sounding invention.

Laura's plan is actually even more diabolical: she sends Phyllis to bring the bomb in a wrapped package to the warehouse; further, Laura gets there first and clubs Phyllis unconscious just before the bomb explodes, intending murder as well as arson. But Phyllis survives the explosion-—only to be charged with Laura’s murder.

Perry agrees to defend her and stages an elaborate demonstration in the courtroom, using Paul, flying in a helicopter forty miles away, to make a key point.