To avoid being blackmailed for $100,000, an engineer with friends in high places asks Dennis and his team to recover some indiscreet letters from his youth which he wrote to a former lover.
After a reporter is murdered, the crew at 21 Beacon Street set out to gain access to a safe containing a syndicate payroll which includes several prominent politicians.
Chinese communists kidnap a nuclear scientist. To rescue him, Dennis hides in a shipping container bound for the import facility where the scientist is being held.
A gang decides to steal the receipts of a mail order and decide to target the head cashier George Manning. The hoodlums kidnap his wife Lois promising to release her when George hands over the cash.
Killer is found not guilty. Later, he confesses to his new fiance, who then fears for her life. Since killer can't be arrested by the police due to double jeopardy, she calls on the folks at 21 Beacon Street for help.
When the two owners of a jet engine company are found murdered, the chief suspect is a con artist who was trying to bilk one of the brothers. But Morgan thinks it all looks TOO obvious.