Following the murder of his father Albert and brother Herbert, Jason Thomas is arrested for the crime and retains the Prestons to defend him. At first, they doubt their client's sanity; however, when he completely loses control in the courtroom provoking another attack, everyone begins to question if his flamboyant outbursts are simply an act to support an insanity plea.
Loose-living party girl Norma Burgess fends off the drunken advances of David Fry. When the altercation turns violent, Norma shoots him in self-defense. The Prestons take Norma's case after the district attorney decides to indict her for attempted murder.
Joanne Rawlins seeks legal assistance from the Prestons to arrange a release for her husband Frank, a businessman who has been detained and arrested in Moscow on suspicion of spying. The Russian government agrees to exchange Frank for Vorchek, one of their own citizens jailed in the United States for espionage. The Prestons agree but then find themselves in a quandary when they learn that Vorchek will likely be executed upon his return to Russia.
The Prestons are retained by Raul and Suzy Martinez in what appears to be a routine eviction case. However, unbeknownst to them, Peter Cole, a local political bagman, has been ordered to ensure the eviction. Cole seeks help from Judge Phillip Benning, whose loose ethics allow him to fix small court cases.
When a patient bleeds to death during a routine hernia operation, his widow wants answers, yet she finds few forthcoming, so she asks the Prestons help. The lawyer and his son work on the case, finding the doctors and staff of the hospital closing ranks, except for a young intern with a guilty conscience.
Assistant district attorney Cliff Sellers finds himself on the end of a very cruel hook when he's assigned to prosecute the case of Walter Wyatt, a man accused of murdering his spouse. Sellers secretly knows that the defendant is innocent: his brother Tim was having an affair with Mrs. Wyatt and impulsively strangled her when she threatened to expose their relationship. As the trial begins, Sellers is torn between loyalty to his brother and the horrifying possibility that Wyatt could face death in the electric chair for a crime he didn't commit.
Young but impoverished lovers John Strafaci and Theresa Sullivan want to marry but can't afford it. They impulsively decide to rob a liquor store to finance their marriage, but are caught, arrested, and face up to 30 years in prison each if convicted. The court appoints the Prestons to represent the couple, and the attorneys mount a rather unorthodox defense to save them.
While in pursuit of a suspected thief, police sergeant Henry Olson violates departmental procedure by firing a shot into a public crowd. When he discovers that an innocent bystander has been wounded by his bullet, Olson attempts to cover up his culpability by framing fellow officer Don Franks.
In a change from their usual work, the Prestons undertake to look after the legal business involved in getting a play through a tour and onto Broadway.
A decade after being blacklisted in Hollywood for his political ties, former actor-turned-shoe-salesman Joe Larch receives an offer for a comeback in a new film. When Larch's plans are thwarted by a radical political group pressuring the town's mayor to stop the production, Larch hires the Prestons to file a libel suit against his enemies.
Acting out of conscience, nuclear scientist Dr. Daniel Orren destroys the results of his own research - and is charged with destroying classified documents.
The Prestons take the case of respected pharmacist Ed Clark, who is arrested after being caught selling narcotics without a prescription to young addict Tom Grafton. During the case, the Prestons learn that Clark has been selling to other addicts too out of symphony for his wife Anne, who harbors a secret addiction of her own.
During a military training maneuver, Private Collier is killed in accidental fall. Jerry Hegen, a tough, brutal Marine drill sergeant faces court marital following the death of Collier, a recruit Hegen had bullied. The Prestons are called upon to defend Hegen.
The Prestons take the case of Steve Lucas, a hood indicted in a manslaughter case. When the trial ends with a hung jury and a new trial is ordered, one of the jurors, cabbie Louis Brandt, is offered $5000 to ensure a "not guilty" vote. However, the bribe is later exposed, and Brandt falsely identifies Ken Preston as making the offer. Lawrence must then defend his son against the charge.