"Spy pictures" refers to photographs or images taken secretly or discreetly, usually of something or someone that is being observed or investigated without their knowledge.
Sentences with «spy pictures»
We present now, the first spy pictures showing the new model with the production headlights and tail lamps mounted. (mercedesblog.com)
Exclusive spy pictures show the model being prepared for its Chinese debut. (mercedesblog.com)