This isn't really a mystery but more suspense with really wonderful, unique characters. I enjoyed the trek to get revenge on the people that killed Ash's brother and how exactly they'd get justice. It is fabulous, if terrifying, to have a female assassin to content with. A nice, unexpected twist. That ending is awesome, great fight and sweet HEA. The only reason this fantastic book isn't getting five stars is for the head hopping, so annoying.
The Collector is a must read for romantic suspense readers!