Simon R. Green 
Dr. DOA [EPUB ebook] 

My name is Eddie Drood, and I’m running out of time…Eddie has been fatally poisoned. Not even his most powerful allies can save him. Certain death awaits, and Eddie is determined to find out who poisoned him before he succumbs. Eddie soon learns that there is only one person who could be behind the attack: Dr. DOA. Even the most formidable in the underworld are afraid to whisper Dr. DOA’s name, and no one knows where Eddie might find a man who operates in the darkest shadows. But Eddie has his heart set on revenge. With his health failing and time running out, he has to catch up to Dr. DOA before his time runs out.