"Three Trumps: A Nero Wolfe Omnibus" is a collection of three novels by Rex Stout, featuring the renowned detective Nero Wolfe. The omnibus includes the following novels:

1. "The Black Mountain": In this novel, Wolfe and his assistant, Archie Goodwin, find themselves involved in international affairs. The story revolves around an Albanian-American businessman, Raoul Karns, who seeks Wolfe's help. Karns believes his life is in danger due to his involvement in Albanian politics. As Wolfe delves deeper into the case, he uncovers hidden agendas and dangerous alliances, leading him to confront the power politics of the Black Mountain region.

2. "If Death Ever Slept": In this intriguing mystery, Wolfe is hired by Otis Jarrell, a wealthy businessman, to investigate threats against his daughter's life. Jarrell's daughter, Neya, is married to one of her father's business partners, and someone seems determined to harm her. As Wolfe looks into the matter, he uncovers a complex web of family secrets, personal rivalries, and corporate espionage. He must navigate through these murky waters to uncover the truth and protect Neya from the looming danger.

3. "Before Midnight": This novel sees Wolfe drawn into a case involving a prominent New York senator, Orson Milbank. Milbank hires Wolfe to investigate a series of threatening anonymous letters he has received, which could potentially ruin his political career. As Wolfe digs into the senator's past and begins to question his staff and associates, he uncovers a network of lies, blackmail, and betrayals. Time is ticking, and Wolfe must solve the puzzle before midnight to save the senator's reputation.

Each of these three novels combines intricate plots, engaging characters, and Rex Stout's signature writing style. As an omnibus, "Three Trumps" offers readers the opportunity to experience multiple thrilling adventures of Nero Wolfe in a single volume.