Sherlock Holmes: Revenant — William Meikle

A strange sickness affecting the members of the House of Lords starts a new adventure for Holmes and Watson, one that will see them on the run, accused of murder and pursued by both the police and a deadly gang of assassins.
The case takes them up and down the country, from Scotland to the Houses of Parliament and leads them down arcane paths, following their relentless foe in pursuit of the lost secret of immortality.
Their adversary seems hell-bent, not only on their destruction but on an act of terrorism that will shake London to its foundations.
Holmes must catch and unmask the revenant, and only by confronting his own past will he be able to prevail.