33 Half Moon Street is a detective drama about Assignments Unlimited, an agency at that address, run on the promise that it will do anything, anywhere, at any time. That premise is what sets it apart. There is no private eye waiting for a corpse here; the series is about hired help, and the mysteries tend to arrive dressed as chores. Two women want a hole dug to the exact size of a grave, and a worker who will keep quiet about where it is. A man who saw the agency's advertisement in the Times wants his garden in East Croydon cleaned up in a hurry. A travel firm on the Old Brompton Road needs someone with an international heavy vehicle license to drive tourists through France and recite passages from a guidebook. Another client wants a strong man who knows the lower reaches of the Thames and will not look out of place dressed as a Viking. Each errand opens onto something darker. The grave-digging job turns up a cleric battered to death, and a silver chalice with precious stones hidden under a layer of lead. The garden job leads to a buried ring and questions about a plane that went down in the Irish Sea. The coach tour ends with foreign agents, a shooting and a time bomb. On a building site in 'The House That Seamus Built', someone has set caged sewer rats to chew through the sealing boards, and the man meant to be watching the site admits a woman called him away to the fence. The cases are treated as agency files, and in 'Ring Of Roses' a closing line comments on whoever titled the file. Much of the storytelling comes as first-person narration from an operative, named Carson in more than one case, who trades banter with an inspector and rarely lets a scene end without a quip. He turns down a reward with a crack about his mother-in-law, and after a spy plot built around a travel book he asks the inspector whether he has read any good books lately. 'The Norse Opera' is the broadest of the lot, pairing a peaceful abduction with a hired man who says the only university he ever attended was a heifer branding in Colorado. Its punchline turns on a costume-shop weapon that was supposed to be wooden and was not. The series can also turn quiet and grave. 'The Man Who Thought Too Much' begins with a frail, tearful woman from Wood Green who fears for her husband and her baby and will not go to the police. Period detail runs throughout, from a sixpence for a phone call to jobs priced in pounds. New listeners get the clearest view of the formula from 'Three For The Omnibus', and the lightest one from 'The Norse Opera'.