A death in the House of Commons has all eyes on foreign shores. But what if the killer lies closer to home?

London, 1924. Westminster is in an uproar when a promising young clerk is found dead at his desk, killed by a powerful poison sent by post. Worse yet, the letter was addressed to his boss - the Leader of the House.

Dora and Rex, with the help of Clark and Prudence, must determine who sent the killer letter and why. Between political parties jostling for power and enemies plotting overseas, there is no shortage of suspects.

Can the bright young foursome find the killer before he strikes again?