I've enjoyed the two earlier books in this series (see here and here) about Big Red and Old Red, the Amlingmeyer brothers, as well as the occasional story about them in EQMM (in fact, the latest story in the magazine shares the San Francisco setting of this novel and is briefly alluded to in Big Red's narration). This time the boys find themselves in Chinatown, with Gustav (Old Red) still applying the methods of Sherlock Holmes, this time to a supposed suicide that's actually a murder. (Some of the characters, including the murder victim, appeared in the previous book in the series, but you don't have to have read that one to enjoy this one. Trust me.)
Before long, the Reds are up to their necks in trouble as they try to find the elusive Black Dove while being pursued by various hatchet men, the cops, vengeful madams, crime bosses, and such. Both Reds are a bit distracted by the presence of the lovely Diana Corvus, who's sure to return in future books, and we find out a bit more about the background of Old Red, who's been harboring a secret for a long time. Check it out.