Languishing in an Imperial detention centre, Lieutenant Kage - convict soldier of the 13th Penal Legion - is at the end of the line. That is, until his ruthless old commanding officer returns with one more deadly assignment. Now Kage must whip into shape a new team of the very worst the Imperial Guard has to offer, before leading them on their one and only mission: to assassinate a warmongering enemy general, one of the mysterious alien Tau!

Read it because
The second book in the Last Chancers series by Gav Thorpe.