The 3-E students head for the lair of the enemy to stop a deadly biological attack. But blocking their path are three master assassins: Smog, Grip and Gastro, who excel, respectively, in the use of poison, brute strength and guns.

With their teacher Karasuma down, Karma and his friends face terrible odds. And even if they defeat their foes, how will they wrest the antidote from them?

Worse, it turns out the mastermind behind the attack is someone they know...