Alright, I've arranged my storyline into two options for a "main quest" and three proposed "side quests." Hopefully we can make something fit. I can provide any necessary background on the assassins, the faction of the Alerian government that funded them, the Tap plague, or anything else that requires further detail.

MAIN QUEST (option A)
Title of Mission: Kill the Breaker
Brief Synopsis of Mission: Sixteen Aleraran assassins are in an airship bound for Corone. They will sailchute down over strategic locations by darkness, the last one killing the airship’s pilot as she goes. Upon landing they will attempt to perform a simultaneous spell using synchronized watches, tainting the Eternal Tap on Corone so that anyone who uses it will become afflicted with an illness similar to leprosy. At this point the only way to safely channel magic from the Eternal Tap on Corone would be through the filters built into their scabbards. Four of these assassins, led by the single-minded Vityr Sha'keth, will converge on Joshua Cronen in an attempt to kill him. Work with the Alerarans in an attempt to bring down a demigod, or lend your assistance to Breaker as he strives to fight back in a weakened state.
Number of Players: 4 Maximum
GM: Breaker
Closed
Quality Expectation: 3

MAIN QUEST (option B)
Title of Mission: All Nightmare Long
Brief Synopsis of Mission: Sixteen Aleraran assassins are in an airship bound for Corone. They will sailchute down over strategic locations by darkness, the last one killing the airship’s pilot as she goes. Upon landing they will attempt to perform a simultaneous spell using synchronized watches, tainting the Eternal Tap on Corone so that anyone who uses it will become afflicted with an illness similar to leprosy. At this point the only way to safely channel magic from the Eternal Tap on Corone would be through the filters built into their scabbards. After the spell the assassins fade into the night, each with their own mission designed to dismantle Corone's defenses and infrastructure in advance of a full-scale invasion. Work with the Alerarans in their attempt to topple a nation, or join Breaker in fighting and plotting against them.
Number of Players: 4 Maximum
GM: Breaker
Closed
Quality Expectation: 3

SIDE QUEST
Title of Mission: The Tap Tinker
Brief Synopsis of Mission: Breaker and Am'aleh, both suffering from the taint on the tap, track down Lilthis and enlist her help in fixing the problem. At first they are stumped, but after Breaker manages to procure one of the filters used by the assassins, things start to move in their favor. They are harried by the effects of the taint as well as an attack by an assassin, and realize they will not be allowed to simply work in peace.
Number of Players: 2 (Breaker and Lilthis)
Closed
Quality Expectation: 3

SIDE QUEST
Title of Mission: Hearing Without Listening
Brief Synopsis of Mission: While hunting down a group of bandits Breaker runs into Ayaka, who has created a cure for "ashen lung", a common illness on Corone attributed to the volcanic ash in the air. They work together with the Faith United to mass produce the remedy while running a field hospital near what remains of Serenti. However, Josh is there for another reason; to track down one of the Aleraran assassins who was reported in the area.
Number of Players: 2 (Breaker and Ayaka)
Closed
Quality Expectation: 3

SIDE QUEST
Title of Mission: Datura Midnight
Brief Synopsis of Mission: Felicity was assigned to a botanist team replicating the Ashen Lung cure. However, her age and inexperience causes the head alchemist, Tacita Shiver, to bar her from doing anything. At midnight, a gang attacks the lab in attempts to steal the cure and profit off it themselves. While the rest of the team takes their completed vials to a wagon to get away, Felicity stays behind to fight the attackers. It is here that she must make one of the most difficult choices in her life - shall she dare take life?
Number of Players: 2 (Breaker and Flamebird)
Closed
Quality Expectation: 2