It begins in my lab, and I receive a call. Someone needs to go? Does it have to look like something natural? No? Lovely. The victim will be hosting a banquet to which I need to get an invite? Easily accomplished. A bribe, or a syringe full of tetrodotoxin, and I am a distinguished guest, just for the night of course. Permanently stealing someone's identity would be so boring. I just happen to be a friend of the host, he has a flute of champagne? Ah, a Coke. Darker, and allows me to have ever so much more fun. Ricin, in just high enough doses to cause the pain in every nerve, small amounts of mercury to make it impossible to fully counteract combined with amobarbital to make them unable to scream. The first symptom, a slight lassitude, a feeling of lightheadedness. Then, the amobarbitol starts kicking in, rather fast acting and the victim feels a sudden urge to use the restroom. He gets there usually. Then the ricin begins to taken effect... He might scream once or twice. A minute or so later, he is unconscious, five minutes past that, he is dead.