Nemesis. Cascade Wars, #4

Nemesis is the fourth book in an exciting military scifi series and there are cliff hangers!Captain Monroe thought his nemesis died in the fires of the Founding War. He was wrong. Now the ghost of that brutal conflict has returned-alive, ruthless, and working from within the enemy's ranks to shatter the Federation from the inside. As war spreads across the stars, Commander Ronalds fights a desperate battle closer to home.
Enemy infiltrators stalk his city, civilians are disappearing, and his own family has become a target. Every hour he fails to act brings the enemy one step closer to total control. Beyond the front lines, Thoros-the powerful leader of the Great Families-faces a crisis that could ignite civil war. His wife has been abducted by a renegade Family determined to destroy centuries of tradition and plunge the galaxy into chaos.
With the Federation on the brink, Monroe launches a daring operation that could turn the tide of the war-or doom humanity forever. But to succeed, he must confront the one enemy he swore would never rise again. Nemesis is an explosive military space opera packed with interstellar warfare, political intrigue, deadly betrayals, and relentless action-where old enemies return from the ashes, and every choice carries a devastating price.