Donald Lam and Bertha Cool Books in Order

Donald Lam joins Bertha Cool's detective agency as an operative and process server. Their case develops into a legal puzzle involving a confessed killer whom the courts seem unable to convict, testing Lam's ingenuity and Cool's practicality.

Hired to investigate a husband's possible infidelity, Donald Lam uncovers activity more dangerous than an affair. The husband's murder shifts the assignment toward protecting a young woman from prosecution, drawing Bertha Cool's agency into trouble with the police.

Donald Lam suspects blackmail when a woman pays out large sums and questions a mining company's claimed gold discovery. His inquiries bring together fraudulent investments, dangerous acquaintances, and a murder that attracts unwelcome attention from the police.

A client calling himself Mr. Smith hires Cool and Lam to find a woman missing for twenty years. Donald's inquiries into her vanished marriage attract violence and uncover troubling questions about the man paying for the search.

A doctor hires Donald Lam and Bertha Cool to recover stolen jewels, bringing them into his troubled household. The investigation becomes a fight against a killer, with personal entanglements and financial motives complicating their search for answers.

Recovering from illness, Bertha Cool joins Donald Lam in searching for a missing bride-to-be. Their assignment leads into slot-machine fraud, a dishonest client, and murder, making a straightforward disappearance part of a much larger criminal scheme.

A blind man hires Bertha Cool to locate a young woman who has vanished. He can describe her voice and manner rather than her appearance, giving the detective an unusual starting point for her missing-person investigation.

Roberta Fenn's ambitions place her in danger from blackmail, betrayal, and murder. Bertha Cool and Donald Lam try to untangle the threats surrounding her, knowing that a mistaken judgment could leave the woman they seek to protect dead.

Bertha Cool accepts what looks like a routine assignment involving a client's financial trouble. Anonymous letters, a missing wife, and a corpse in his basement quickly turn the job into a murder investigation she struggles to control.

Donald Lam and Bertha Cool investigate a bistro where discreet encounters lead to profitable blackmail. A murder disrupts the operation, and the weapon left in Donald's car threatens to entangle the detectives in the crimes they are trying to solve.

Donald Lam investigates why a generously supported young woman has sold valuable jewelry. A guardian's murder beside his pet crow turns the inquiry dangerous, and tracing the jewelry may offer a better route to the truth than trusting the surviving guardian.

Donald Lam and Bertha Cool are hired to stop a suspected poisoning before it happens. Donald devises an anchovy-paste publicity scheme to distract the potential killer, but its failure leaves the detectives juggling bodies, witnesses, and increasingly unwelcome police attention.

A routine assignment shadowing a man courting a wealthy woman leads Donald Lam to a disreputable hotel. Two corpses make him the police's prime suspect, forcing him to outmaneuver investigators while finding the killer who threatens his partnership with Bertha Cool.

A man connected to a gangster's missing girlfriend hires Donald Lam to establish an alibi. His story soon breaks down, sending Donald into a mining scam, an illegal casino, and two murders that threaten any chance of collecting his reward safely.

Donald Lam and Bertha Cool travel toward Hawaii to protect wealthy young widow Mira Woodford from suspected blackmail. Questions about her older husband's sudden death and the people surrounding her soon turn the assignment into a murder investigation.

A client asks Donald Lam and Bertha Cool to locate a man who supposedly supplied an idea for a story six years earlier. Donald discovers that the client is no writer and the missing man was shot, reviving a dangerous old mystery.

Donald Lam travels to San Francisco to help a client threatened with exposure of an indiscretion. The woman supposedly behind the threat denies blackmail, leaving him to untangle a situation that differs from the story he was told.

Donald Lam and Bertha Cool are hired by a Texas businessman to locate Yvonne Wells. Her husband's refusal to cooperate and a neighbor's account of a body turn a straightforward search into a possible murder investigation.

Bertha Cool and Donald Lam are hired to safeguard an adventurer's collection during a dinner party. When treasures disappear despite searches of the guests, the detectives must explain an apparently impossible theft before the case becomes more dangerous.

Daphne Beckley hires Donald Lam to establish what happened to her missing husband. Whether she receives an insurance windfall or seeks divorce and alimony depends on his answer, giving the investigation unusually complicated financial stakes.

Hazel Downer hires Donald Lam to find the husband who vanished with her money. An armored car robbery involves the same missing sum, drawing Lam and Bertha Cool into a case already attracting police suspicion.

Donald Lam investigates leaks of confidential business information while Bertha Cool urges him to avoid dangerous assignments. A murder at a motel connects their respectable client to another investigation involving a prowler who watches the guests.

A routine investigation of an insurance claim leads Donald Lam and Bertha Cool toward murder. Lam poses as a former convict to infiltrate a criminal gang, risking his safety as the assignment grows beyond a simple car accident.

Carleton Allen hires Bertha Cool and Donald Lam after a night with another woman coincides with a motel murder. Lam doubts his account, but the tempting fee pulls the detectives into a dangerous tangle of blackmail and deception.

Donald Lam and Bertha Cool agree to provide continuous protection for a secretary receiving threatening messages. The arrangement raises Lam's suspicions, and investigating the people behind it brings the detectives into a case involving murder and conflicting stories.

Homer Breckinridge hires Donald Lam to examine an insurance claim, delighting Bertha Cool with the prospect of respectable work. Lam soon discovers the investigation is dangerous, putting him at risk while he tries to understand what lies behind it.

Clayton Dawson hires Donald Lam and Bertha Cool to protect his family's reputation by watching an unruly daughter. The apparently limited assignment soon brings murder and blackmail, forcing Lam to confront dangers hidden beneath the client's request.

Bertha Cool accepts a profitable blackmail assignment despite Donald Lam's misgivings. Worthless photographs, a fatal dinner, and a series of double-crosses turn the investigation into a murder case with Lam himself positioned as the obvious suspect.

Bertha Cool welcomes a client seeking an investigation into suspected insurance fraud, but Donald Lam doubts the assignment is straightforward. Searching for evidence draws him into a trap whose apparent respectability conceals a threat to the detectives themselves.

A wealthy client's search for a missing man conceals a different interest in a missing woman. Donald Lam and Bertha Cool follow the apparently minor assignment into a larger mystery involving deception and an unusual smuggling operation.