The Penny Küfer Investigates series by Alex Wagner

Penny Küfer starts her dream job as a detective—only to be disowned by her snobbish mother and dumped by her greedy fiancé. Her only comfort? A luxury trip on the Occident Express. But before she can sip her first champagne, a corpse turns up—in her own compartment, no less!

Penny Küfer, aspiring sleuth, finds herself in a “lost place”, a former grand hotel in the foothills of the Alps. Recently a particularly devious murderer seems to have checked in, plus there is a strange rumor about a secret hiding place full of diamonds…

Axel Sandorf, business magnate and visionary, has achieved what others have only dared to dream about: he is cruising the oceans aboard the largest private submarine yacht the world has ever seen.
Penny can’t believe her luck when she, of all people, receives an invitation from the elusive billionaire. But murder is just around the corner…

Has Niní Delight, the head of a luxury lingerie chain, really taken her own life with arsenic? The police have ruled out foul play. But—as Penny will soon discover—nothing is what it seems in the world of silk, French lace, and glamour…

Penny Küfer’s latest assignment feels like a walk in the park: She is supposed to ensure the safety of a world-famous shipowner and his fiancée on the maiden voyage of a stunning new cruise ship.
But what sounded like luxury and relaxation on the high seas quickly turns into a survival trip.