Imagine you could genetically engineer a microorganism that was able to produce LSD into its culture broth. If the microorganism was a brewing yeast you could make beer spiked with homemade LSD. Imagine how much mischief you could cause with that. If the microorganism was a bacterium that you had also engineered to transfer LSD-synthesis to every other bacterium in a person's body, you could make some very potent live yoghurt. Imagine what sorts of mischief you could do then. Follow Karen Spencer, an investigator with the Plasmid Control Commission on her first solo field mission as she identifies exotic microbes like these and pursues those who created them and put them to use. And all the time she is chasing them down, the greatest mischief these microorganisms have caused is being played out in the dizzying depths of the North Atlantic.