These are mysteries with historical and cultural content. Mortensen is a fun and good-natured hero who trots the globe and travels throughout history. Educational back matter offers the readers more information on the topics covered.

In Transylvania, 1891, seven people have been found dead with bite marks on their necks. Mortensen knows better than to be superstitious, but how else can he explain this murder spree? When a young tourist named Maya survives a similar attack in Prague, Czech Republic, in 1993, Mortensen learns the truth--a time traveling crime lord has been stealing kidneys from living victims! Mortensen needs to track down Maya's kidney before it's too late.