It's hard to mount much of a defense for a killer once he's confessed. But since Helen Van Geer doesn't want to see her son Stewart hang for his father's murder, she hires the Big River Detective Agency (No Justice, 1996, etc.) to dig up evidence on his behalf. Masey Baldridge, the Confederate veteran turned Big River's heavy-drinking investigator, spends most of his time sick, and ex-working girl Salina Tyner most of hers following up false leads. So this time it's up to their partner, riverboat captain Luke Williamson, to do the serious detecting, even though he's been the late Hudson Van Geer's most serious rival on the Mississippi. Good stuff on the steamers' real rivals, the infant railroads, which Brewer's fourth works neatly into the plot. The trimmings this time, though--from black magic to Luke's revisiting an old romance--never seem to be aboard for more than the ride.