In the short story Christmas Adventure, Oscar Levering part of a brother-sister pair who had succeeded in stealing a precious ruby belonging to an unnamed nobleman. As Oscar was engaged to marry Evelyn Haworth, he had been invited to the Christmas house party hosted by Miss Emily Endicott, Evelyn's aunt. Poirot had been commissioned to recover the ruby. He knew something of this pair of jewel thieves and suspected them. He thus secured himself an invitation to the same house party through Squire Endicott. Through a ruse set up by Poirot, and with the help of Nancy Cardell, Oscar became worried that he might be implicated in a killing at the house party. He then fled the scene taking only a paste copy of the jewel.
Oscar's role in the story is comparable to that of Desmond Lee-Wortley in the expanded story The Adventure of the Christmas Pudding, the only difference being that Miss Levering was really his sister and not just a cover name adopted by an accomplice.