Ironstone Saga Series by Keith McArdle

Vyder Ironstone is an assassin with a troubled past. At the order of his king, Vyder must undertake his most dangerous mission yet. A mission from which he may never return.If he is successful, it might just be enough to alleviate war tearing the kingdom apart.The prospect of failure is not worth considering.

Assassin-for-hire Vyder Ironstone is on a mission for the King of Wendurlund. While the pay’s good, the odds are not, since the task requires him to travel deep into enemy territory. But first, there’s the little problem of his death to overcome, not to mention a malcontent travelling companion with no love for humanity and a deadly purpose of his own... moreAssassin-for-hire Vyder Ironstone is on a mission for the King of Wendurlund. While the pay’s good, the odds are not, since the task requires him to travel deep into enemy territory. But first, there’s the little problem of his death to overcome, not to mention a malcontent travelling companion with no love for humanity and a deadly purpose of his own. Vyder had better find a way to deal with both, and quickly, because, controlled by an unseen power, hordes of giant spiders have attacked the capital. Facing vast numbers, Commander Tork of the King’s Own and his small troop of elite soldiers won’t be able to hold the walls for long. Vyder’s quest is vital: he must not fail, or the empire will fall. less

As the invading army of a mad king ravages the land, Vyder seeks help from the one force that can stop them: the fierce Highland warriors of his home province. But Vyder finds he has enemies in the Highlands now -- can he stay alive long enough to raise an army, and even if he succeeds will it be too late?