This is a new mystery featuring Detective Constable Sally Bithron.The death of a police informant provokes questions at Government level leading to the task least loved by any the law enforcement officer - that of investigating your superiors for evidence of malpractice or corruption.Sally Bithron, first encountered in "Hear Me Talking To You", is assigned to assist Assistant Chief Constable Esther Davidson in the enquiry.Initially it is an escape from domestic problems for both women, but it soon turns uncomfortably personal as they both become involved in a complex web of deceit and the way power corrupts.And when a senior policeman apparently commits suicide, in the same place as the informant, Sally and Esther have to ask some uncomfortable questions - and find that they are prevented from doing so by the powers that be."Tip Top" investigates questions whether police informants are given sufficient protection, and whether guidelines and reporting structures within the force are sufficient - or is corruption and betrayal rife?