In The Big Present, detectives Joe Friday and Frank Smith are assigned to the burglary detail in Los Angeles, where they face a perplexing case involving a thief dubbed the 'Milk-Bottle Bandit.' Over the past two months, this elusive criminal has pulled off eighteen consecutive burglaries, leaving behind only empty milk bottles at each scene. The detectives are puzzled by the lack of substantial leads and the seemingly trivial nature of the stolen items, which include petty cash and candy. They suspect that the thief might be a juvenile, given the evidence and the method of operation.