Lena Bloom, an ordinary clerk in London, gains the ability to communicate with rodents and insects after being struck by lightning on a stormy night. She assists the police in solving cases for reward money. Building an intelligence network of rats, cockroaches, flies and other small creatures, she cracks tough cases including serial murders, workplace sexual assaults and a seven-year cold case. Evolving from a timid, cash-strapped employee to a special police consultant, she chases justice amid fantasy and reality.