Once Batman has reappeared on the screen, you will have to start walking to the right, and collect a Batarang for fifteen shots of it; once you've done so, two brown-suited gangsters shall come walking towards you. Once you have thrown two Batarangs at both of these to kill them (they are worth 50 points for the first hit and 800 for the second) you will have to jump up to a platform and collect a Batrope for fifteen shots of it (once you have done so, the text "FIRE BATROPE UP TO GO UP A LEVEL" will appear on the screen) - and you will then have to fire a shot from the Batrope up to another platform and jump up to a third one in turn, then jump (to the left) onto a fourth platform as a third brown-suited gangster comes walking towards you while firing shots at you (which you will have to jump to avoid). Once you have fired two more shots from the Batrope at him to kill him, a brown-jacketed thug will emerge from an elevator; once you have fired a shot from the Batrope at him to kill him (killing them this way is only worth 240 points) you shall have to collect a Bat-Symbol for an extra hit, jump back to the right over to the third platform and continue walking to the right (while watching out for drops of toxic waste dripping out of four nozzles overhead) for twenty-four more seconds. Batman shall also die instantly if he falls into any of the vats of toxic waste in here.
You'll then have to drop down to a fifth platform and collect a Gas Grenade for fifteen shots of it; once you've done so, you will have to jump on a fourth brown-suited gangster twice to kill him (killing them this way is worth 300 points for the first hit and 2400 for the second) and land upon a sixth platform. You'll then have to jump onto a seventh, vertically-moving platform and walk back to the left onto an eighth (static) one as a fifth brown-suited gangster comes walking towards you while firing shots at you - and once you have thrown two Gas Grenades at him to kill him, you shall have to collect another Bat-Symbol for another extra hit (although it still registers the number on the Bat-Symbol representing Batman's current life does not go higher than 6). You'll then have to walk back to the right, drop down to the ground, and continue walking to the right again for twenty-four more extra seconds of time.
A sixth brown-suited gangster (and a gray-suited one) will then come walking towards you while firing shots (and throwing gas bombs) at you; once you throw two more Gas Grenades at both of them to kill them, a green-jacketed thug shall emerge from a door. Once you've thrown a fifth Gas Grenade at him to kill him (killing them this way is also only worth 240 points), you have to jump up to two more (static) platforms in turn as another brown-jacketed thug comes walking towards you - and once you have thrown a sixth Gas Grenade at him to kill him you will have to jump up onto an eleventh platform (and collect a third Bat-Symbol for a third extra hit) as a seventh brown-suited gangster comes walking towards you while firing shots at you. Once you have thrown two more Gas Grenades at him to kill him two more brown-jacketed thugs will emerge from another door; once you have thrown two more Gas Grenades at both of them to kill them you shall have to drop down onto a twelfth (horizontally-moving) platform and jump up to a thirteenth (static) platform in turn as an eighth brown-suited gangster comes walking towards you while firing shots at you. Once you've thrown two more Gas Grenades towards this particular gangster to kill him, you will have to continue walking to the right once again, to receive twenty-four more extra seconds of time.
You'll then have to drop down onto a fourteenth (static) platform and punch another gray-suited gangster at close range twice to kill him; once you have done so, you will have to collect another Batarang, for fifteen more shots of it. You will then have to drop down onto a pipe and the ground in turn, while watching out for more drops of toxic waste dripping out from four nozzles overhead, for twenty-four more extra seconds as another green-jacketed thug emerges from a third door - and once you have thrown a Batarang at him to kill him you will have to collect another Gas Grenade for fifteen more shots of it as a ninth brown-suited gangster comes walking towards you while firing shots at you. Once you have thrown two Gas Grenades at him to kill him, you shall have to collect a fourth Bat-Symbol for a fourth extra hit; once you have done so you shall have to jump up to a fifteenth (static) platform as a third gray-suited gangster comes walking towards you while throwing gas bombs at you. Once you have thrown two more Gas Grenades at this one to kill him, you will have to jump up to a sixteenth (static) platform while avoiding a third Batarang (because Gas Grenades will be more useful in the next stage), then wait for a fourth gray-suited gangster to drop down to it - and once you've thrown two more Gas Grenades at him to kill him, you'll have to jump up to a seventeenth (static) platform for eighteen more seconds as you come to Jack Napier himself (who, due to his purple suit, looks like Pinky McFingers out of Teenage Mutant Ninja Turtles, and Konami's arcade game of that show also used a Yamaha YM-2151 FM sound chip for its music).
Napier shall then say Nice outfit! from the MSM-6295 as he starts firing shots at Batman; once you have crouched down and kicked him at close range enough times to force him off the edge of the platform (he is worth 100 points for every hit, but can walk back to the left), he will scream from the MSM-6295 as he falls into a vat of toxic waste (mutating him into the Joker), and you'll receive a 2500-point bonus as Batman fires a shot up to exit the plant.