Reggie and Nigel Heath are close in age but worlds apart in personality. The older of the two brothers, Reggie is a successful attorney with charisma to spare. Nigel has always struggled to step out of his shadow. When they lease office space on Baker Street, the paperwork comes with an odd stipulation: his firm must receive and respond with a standard reply to letters sent to Sherlock Holmes, who famously occupied the same address. Then Nigel, who becomes intrigued with one of the "Dear Sherlock" notes, disappears quite suddenly.

In Los Angeles, a geological surveyor maps out a proposed subway route--and then goes missing. His eight-year-old daughter, in her desperation, turns to the one person she thinks might help--she writes a letter to Sherlock Holmes.--From publisher's description.

Reggie is thrilled when he learns that his new office is in the same space where famous sleuth Sherlock Holmes used to ply his trade. However, when he starts to receive mysterious mail, written for Holmes, his excitement soon turns into intrigue. As Reggie's brother, Nigel, begins to investigate one of these letters, he inexplicably disappears. Now, Reggie must find his brother while simultaneously solving a murder case.