If you are not sure who the Ghosts are allow me to help.
In the 41st millennia their is only war. The Imperial Guard are the countless legions of Mankind's military might. Each of the billion planets within the Imperium must volunteer regiments of soldiers as tithe to the war effort.
Commissars are those who keep the discipline. They enforce with sword and bolter, order within the ranks. They keep watch for sedition, corruption and cowardice.
Commissar Gaunt has received a rare promotion he has been given command and is now one of the rare Colonel-Commissars. His arrival on Tanith the planet of larger then life ever shifting forests is followed but the destruction of the planet. Leaving only the single regiment under his command.
The Tanith 1st and Only. They are the lost with no home to return to. They are dead walking. They are invisible souls wandering the stars. They are the Ghosts, they are...
Few authors do such a good job with military pulp. Dan Abnett not only does a good job, he rocks it. If you ever look for a military science-fantasy fiction. Each character breaths their own words, you catch glimpses of their true selves each time the words pass over them in the story. Over time these passings layer over each other and you come to like and care for these lost warriors.
This is a future of war and there are losses through the series. Do not expect to have your favorite characters make it out of each dangerous mission. They will die. More will be added to the meat grinder and the cycle of loss and death will continue.
So when you get a chance read this series. Learn about Try-Again Bragg, Scout master Mkoll, the criminal Rawne, and strong Tonia Criid.
Each book is well put together and each mission has a start level of danger. The attention to detail and the pace of each engagement is astounding. I've yet to find action so well told and so complex without getting lost in the specifics.
This is not about inhuman Space Marines, warp touched Inquisitors, or strange Aliens. This is about men and women caught up in a endless war and suffering. You see the loss and you feel the victories as bitter sweet as they are.
No one is safe.
But that's the life of the ghosts. One day they may win a home. One day they may be buried in the stars or countless planets. One day they may come and fight on a world that will take everything.
Read this series. You will not be disappointed