Among the tangled waterways and giant anacondas of the Brazilian Rio Negro, an enigmatic scientist is developing a drug that could alter the lives of women for ever. Dr Annick Swenson’s work is shrouded in mystery; she refuses to report on her progress, especially to her investors, whose patience is fast running out. Anders Eckman, a mild-mannered lab researcher, is sent to investigate.

A curt letter reporting his untimely death is all that returns.

Now Marina Singh, Anders’ colleague and once a student of the mighty Dr Swenson, is their last hope. Compelled by the pleas of Anders’s wife, who refuses to accept that her husband is not coming home, Marina leaves the snowy plains of Minnesota and retraces her friend’s steps into the heart of the South American darkness, determined to track down Dr. Swenson and uncover the secrets being jealously guarded among the remotest tribes of the rainforest.

What Marina does not yet know is that, in this ancient corner of the jungle, where the muddy waters and susurrating grasses hide countless unknown perils and temptations, she will face challenges beyond her wildest imagination.

Marina is no longer the student, but only time will tell if she has learnt enough.