Night of Dangers (The Adventurers Guild #3) by Zack Loran Clark, Nick Eliopulos

An ordinary day at the market comes to a fatal end when a rare Danger infiltrates the city, leaving over a dozen dead. Tensions come to a boil as the city is threatened by upheaval from within and becomes alight with terror. Brock finds himself frustratingly unable to utilize his underground contacts...though the mysterious Lady Grey may not be finished with him yet.

To come together to save their city from a timeless evil looking to settle a score, the young adventurers must learn to trust in each other again and be willing to do whatever it takes to stop the tragedy of the Day of Dangers from happening again.