Operation Rhubarb was an MI5 and Scotland Yard joint undercover investigation of Brockeln Belland, a City of London Bank of impenetrable pedigree, that was brought to a violent close ten ago.

One survivor of the blast, now 16-year-old Juliet, is seeking the truth about her parents' death. As the old case notes land on a Scotland Yard Detective Inspector's desk, Juliet's back door inquiry opens a deadly can of worms that the Establishment presumed buried.

Soon, secrets about the 200-year-old institution begin to come to light. But can they take down whoever is behind the crimes, and find out the truth about Juliet's family?