Box detail, with directions for play.
Here's how it worked: you, the good spy, are in pursuit of a bad spy. You've tracked him to his secret lair, tucked into a dilapidated brownstone next to a pawnbroker's. See your shadow on the steps? You're even wearing a trenchcoat and fedora!
Now, you have to get into the hideout. You decide to blast your way in. Subtle, you are not. The instructions tell you: "First you must get into the house. How can you do this? Well, the only way is to 'blow up' the front...and that's just what you'll do." On the top right of the building is a giant red plastic bomb. The instructions say: "Take careful aim at the bomb with your gun and shoot! Hit the bomb on top of the chimney and the front of the house falls down!" And it does!
The whole front panel of the building falls forward, revealing a tense situation: a beautiful blonde girl tied to a box of TNT. The instructions make sure you realize the gravity of the situation: "Holy Fallen Arches! You must watch your step because there is evil afoot inside!"
"Behold! There are two sinister looking characters watching your every move!" continue the directions. "You must erase them from the scene."
Shooting the pictures with the dart gun knocks them clean out of their frames, along with their hidden spies, presumably. But what's this? Apparently one of the spies was "only wounded," and has given "a signal to the Master Spy hidden at the top of the stairs! THE JIG IS UP! OH, WOE, WHAT CAN YOU DO NOW?" The instructions are just as fabulous as the game itself, really. I'm guessing an unemployed screenwriter or English Lit. grad wrote them. But incidentally, wouldn't the "jig is up" moment have been when you blew the front of the hideout off? A logical misstep, there.
Anyway: as the top picture is knocked from its frame by your dart, it releases a catch holding the Master Spy in place behind the curtains. He begins clacking his way down the staircase, "hurrying to the bottom to 'do in' that poor, innocent girl tied to the TNT box..."
This is when the tension really ratchets up: the Master Spy descends alarmingly quickly on his way to the detonator, and as usual, the instructions convey the seriousness of the situation: "Take aim...steady now...mustn't bungle it! You must hit him before he reaches bottom. If you don't, he'll push the lever and...ZOWIE! But...if you're quick and have a sharp eye, you can save the girl...you're a HERO!"
The Master Spy and the girl who needs saving.
Looks she's done for this time...
You can see more pictures of this set, and read the complete, fabulous original instructions, at Sam's Toy Box.