John Castle

Following the death of a loathsome aristocrat, Poirot is stymied by his suspects' ironclad alibis.

When King's family enterprise shatters into pieces and its accountant winds up stabbed, Barnaby digs into rivalries of business and blood-while Jones explores secret Masonic rites.

With seconds to spare, the team manages to warn the Home Secretary about the car bomb and he survives. Juliet is also caught in the attack and is not so lucky – she is paralysed. But the conspirators still have the upper hand and have direct control over a terrified and weakened Prime Minister, who is ready to announce the introduction of "special measures to protect democracy", essentially turning Britain into a dictatorship.

As Adam recovers in hospital, he hears that the country is falling apart. A terror attack on a gas and oil depot has led to energy rationing and people are dying of cold. The media are blaming weak leadership and one media group in particular is peddling anti-Government propaganda. Galvanised by events, Adam discharges himself from hospital and returns to work.

Violet Smith consults Sherlock Holmes over the mysterious cyclist who has been following her on a regular basis. Meanwhile, the efforts of three men, returned from South Africa to defraud her of her inheritance by forcing her to marry one of them, are thwarted by Holmes and Watson. Is there a connection, who is the solitary cyclist and is he really trying to protect her?