Precursor Revenants

Jon Moss is used to doing dirty jobs for politically expedient reasons in far-flung places across the globe. He may not like it, but it's part of the job. Well, it is when you're part of the special forces group known as The Regiment. Sometimes the problem is a dictator, sometimes a whole government. But whatever the problem, The Regiment always finds a solution.
When an unknown comet appears in the skies above Earth, like most people, Jon doesn't give it a second thought. But when the comet is revealed to be a ship, an envoy from a galactic society, it's time for Earth to sit up and listen.
The technology on offer is staggering, but there's a price. The galactics need help with a few small 'domestic problems', ones that Jon and the Regiment are used to solving.
Soon Jon and the unit find themselves deployed off-world, where they must learn to fight in strange new environments and adapt to new weapons to survive.
But, what does this highly structured galactic society really want with humans? And, why have they waited until now to make contact? On the frozen rocky world called Marbel, Jon's team discover that not everything is quite as it seems. It's a hard-fought discovery for which they may just pay the ultimate price.