LONDON — A “hostage,” a search for explosives, heaps of royal jewels and a five-foot silver gilt mace. Welcome to the reopening of Britain’s Parliament, replete with ancient traditions and elaborate rituals, and infused with tension over the country’s looming exit from the European Union.

The restart of government business on Monday started with a speech by Queen Elizabeth II, a significant ceremonial duty that set out the government’s agenda. It paved the way for Prime Minister Boris Johnson’s attempts to navigate the Brexit deadline, Oct. 31, to be back at center stage as lawmakers return to Westminster to pick apart his manifesto.

Hours of royal pomp and stagecraft played out in the halls of Parliament as the queen and her entourage made an elaborate guest appearance at Britain’s government buildings.

The opening was rife with ceremony and symbolism, all of it steeped in history — with some elements dating back to the Middle Ages. Here is a guide.