Prominent local figure Archer Coe was found dead, locked inside his bedroom by butler Gamble. His secretary Raymond Wrede called the police.Detective Sergeant Heath was the first to arrive to the crime scene, followed by district attorney Markham and his friend, amateur sleuth Philo Vance.With the helpful hints dropped by Philo, the coroner completed his examination and deduced that Archer Coe did not commit suicide, but was murdered. The following rounds of questioning revealed that Archer Coe was not a popular man and just about everyone around him has a reason to kill him.The main suspects are:Archer's beautiful niece Hilda Lake, whom he obsessed about and kept under his control by abusing his position as the executor of her trust.Hilda's lover Sir Thomas MacDonald, whose prize-winning dog was believed to be maliciously killed by Archer.Archer's mistress Doris Delafield, who lived in an apartment building right next to his mansion, was cheating on him with Eduardo Grassi.Eduardo Grassi, representing an Italian museum, was about to lose the deal with Archer to buy the collection because Archer found out about him and Doris.And lastly, Heath's favourite suspect, Archer's brother Brisbane; with whom Archer had a serious brotherly feud with.After an enthusiastic pursuit after the missing Brisbane, Heath's hope of using his handcuff within the day failed when they found Doris' dog wounded and Brisbane dead, both hidden in Archer's mansion. The team was back where it started.Philo's investigation also brought out surprising new information on Archer's servants. Archer's Chinese cook Liang was really a graduate from Columbia who specialises in antiques; Gamble was a reformed professional gambler; and Wrede hated his boss and was looking for a new job.It turned out that Archer was killed twice. First it was Wrede, who both hit and stabbed him when Archer refused to give his consent for him to propose to Hilda. Thinking that Archer was dead, Wrede hit Doris' dog with the murder weapon, as it has strolled into the house at the wrong time. But Archer was not dead, he just fainted. He woke up, not realising that he was dying, walked up stairs and began to change for bed. Before he could change into his slippers, the internal hemorrhage caught up to him and he died in a sitting position.Brisbane, who had been reading a detective novel, decided to use the plots described in the story to kill his brother. Not realising that Archer's already dead, he staged the suicide and used a trick he learned from the book to bolt the door from the outside.When Brisbane was closing Archer's bedroom window, Wrede saw him through his apartment window and decided to come back and finish the job. Mistaking Brisbane as Archer, he killed him and hid both his and the dog's bodies in the closets.Philo now knew how Archer died and why his death appears to be both murder and suicide, but he had no way of making Wrede confess. He conspired with Markham to release all of the suspects; and with the help of Sir Thomas and Hilda, finally got Wrede to confess to the crime.
Output: Question: What friend does district attorney Markham bring with him to the crime scene?, Answer: Philo Vance