Turns out that the drugs have various side effects: trembling, nausea, hallucinations, murderous rages and make your head expand and go puffy.
It all goes a bit bollock-shaped as people start succumbing to the drugs and attacking the others whilst they're all trapped inside a locked-up hospital/lab type place. Bit like a low key 28 Days Later.
Still, grand a week? Probably be worth a punt.
Slow moving but decent.