Tyrion travels deep beneath the Guildhall of the Alchemists.
Hallyne the Pyromancer shows Tyrion jars of wildfire, a substance that will burn basically anything—apparently, the alchemists have been discovering stockpiles of the stuff left all over the city, having been created for the late Mad King.
Hallyne says Cersei commissioned ten thousand jars, and the alchemist believes they can meet that goal.
After leaving the hall, Tyrion is summoned by Cersei. On the way, he learns Ser Cleos has arrived with peace terms from Robb.
Tyrion takes the peace terms to look over and sends Cleos to hang out until he needs him.
Traveling in his palanquin, he hears street-side prophets proclaiming the suffering of King's Landing as retribution for a corrupt city and court.
At the Tower of the Hand, Cersei accosts Tyrion over planning to send Myrcella to Dorne. Tyrion argues she'll be safer in Dorne than in a city about to go to war, though.
Cersei cries, and Tyrion tries to comfort her, pointing out their father is doing everything he can to protect them and win the war.
Tyrion hands her the letter from Ser Cleos. He senses Myrcella will now be sent to Dorne, and he also knows who Cersei's informant is as a bonus.