I took a year's break between Lost Fleet #4 and #5, and maybe it's just the lag, but Relentless is the first book in the series that feels pro-forma. Geary is just a few jumps from home, but the powerful Syndicate Reserve Fleet stands between him and safety, and the fleet is desperately short of everything.

There's more sabotage in the fleet, a kind of stasis in the cold war between Geary's most trusted confidants Rione and Captain Desjani, and a thrilling space marine rescue of a prisoner of war camp. That said, the fleet actions are repeats. I think Campbell could've done something interesting here, having the Syndics pound Geary with long range missiles that he is unable to respond to because of ammo shortages, which would've been a chance for more character development, but sadly it's more clashing vectors.

The book ends with their arrival home, and a great set up for the final book in the series.