Seeker
Exposition
Mid Point
Denouement
Inciting Incident
Rising Action
Climax
Resolution
Falling Action
Ideas
Attacks on surrounding towns
Super-natural disaster
Diseased crops in Harvest
Ideas
Spouse dies
People starving
People sick
Solutions
Other towns trade
Witches for help
Seek gem for help
Ideas
Find gem and fight guard
Ideas
Bring gem back to heal lands
Ideas
Find out other countries going through similar things
One of the gems is housed in Westlemire. Either in a vault, or guarded by a creature, or with a person. Something happens and the stone starts misbehaving and causing destruction and death. Briar has some sort of resistance to the power of the gem and is the one to calm it, take it, etc. (Another book in series?)
Invasion by sane or mind controlled
Invasion happens. Surrounding towns attacked up the coast on their way to Sunkeep. Town gets evacuated while Jesper is pregnant.
Jesper will give birth in Sunkeep during a siege in which he dies, giving Briar a driving force. As the gem will be in the city, they can get it/be called to it and kick off the main plot.
Use the power of the gem to turn the tide of the siege.
Using power makes Briar a political target as well as a target of interest in the war. Politicians attempt to use them for their own gains.
Through political reach, Briar learns other countries are also being attacked where a gem is thought to be protected.
Secretly bonded to Briar?
When in life or death situation, is able to call upon a strange power?
The gem in the vault being guarded is fake? Real one already integrated into Briar?