Mr. Monk Is Open For Business is the eighteenth novel based on the television series Monk.

Like the other novels, the story is narrated by Natalie Teeger, Monk's assistant.

It is the third novel in the series to be written by Hy Conrad.

Natalie rents an office for herself and Adrian Monk to make their positions as consulting detectives official.

Lieutenant Amy Devlin soon comes to them asking for help finding a man who shot and killed three people and managed to elude the police.