It's like this you see, one of the runners has an old friend, perhaps a smuggler, who he's known for years. It's no big secret that this old friend has spent alot of time with Terra First, blowing things up for ol' Mother Earth. He gets in contact with the runner friend, and explains that he's heard about the "item" they have, and has a friend who'd like to buy it, and he tries to broker the deal. It's at this point maybe that the runners take a closer look at the "item" and see that it's more than a little corrupted. If confronted with this fact, the old friend flips out and starts arguing in favour of the toxic shaman, putting his case, and giving the runner a real guilt trip about how's this toxic shaman is "different" to the rest. Maybe he storms off.
A little later they get a comm call from the friend, saying that they were right - he's tied to a chair, and he's going to be killed unless the shaman gets the "item". Maybe he's lying for the shaman, maybe not, but does the runner want to play roulette with their friend's life? A complicated drop and exchange ensues which the runners may be able to get ahead of - if they're smart. Look out for the Force 8 toxic spirits, which are spying on them from astral and reporting back their conversations. Ghost help any mages who go astral to try to find the missing friend...
A bit of legwork might pay off enough for them to contact some other members of Terra First who are not so naive, and who may know where the shaman hangs out.