The Black Ice is the second Michael Connelly novel that features Detective Harry Bosch. Harry is the detective on call on Christmas night when a body is found in a local motel. When Harry is not called to the scene, as he should have been, he becomes curious and goes to the scene anyway. Harry learns the body is suspected to be that of Calexico Moore, a cop who went missing the week before. Harry makes the next of kin notification and finds himself drawn to Moore's widow. This attraction mixed with Harry's feeling of being passed over causes more than a passing interest in the Moore case. When one of Harry's own cases appears to be related to the Moore case, he finds himself following the evidence into places even his superiors do not want him to go. The Black Ice is a well written, gritty detective novel whose protagonist is as sympathetic as he is formidable.

Harry Bosch spends Christmas night alone in his house, listening to the police band radio. Harry is on call, but so far nothing has come up to pull him away from his dinner. However, Harry hears a call related to a dead body found in a motel. Immediately Harry knows something is up because he has not been called to the scene, but he should have been. Harry calls the sergeant on duty at the station and learns that the Robbery-Homicide Division was called immediately because the body is suspected to be that of Calexico Moore, a cop who disappeared the week before. Harry goes to the scene and finds a typical suicide setting except for the absence of a note. Harry speaks to the deputy chief and is immediately told he is not to be a part of the case. While they are talking a note is found. Harry talks the crime scene investigator into showing him the note, which turns out to be a simple sentence typed on a sheet of paper.

Harry is given the unpleasant task of informing Moore's estranged wife. Harry is drawn to Sylvia Moore, seeing in her a quiet strength that he admires. While speaking to her, Harry learns that Moore was under investigation by the IAD detectives and that the IAD has a letter they believe Sylvia wrote. Sylvia denies writing this letter. The next morning, Harry is again told to stay off the Moore case. Instead, Harry is given a stack of cases that another detective left behind when he decided to put in for stress-related leave. Harry is told to pick one of the cases and clear it before the New Year in order to improve the division's statistics. When Harry reviews the cases, he discovers that the most recent case, the beating death of a Juan Doe, involves Moore. As Harry begins to investigate this case, he receives a call from Moore's co-workers, telling him they found a case file in Moore's squad car that has a note requesting Harry receive it.

Moore reviews this file, discovering that Moore was putting together a file on Black Ice, a street drug originally from Hawaii that is now being sold by Mexicans. Harry knows this file is intended to answer some questions Harry had about a case of his involving the death of a Hawaiian drug dealer. Moore and Harry met shortly before Moore's death to discuss this case. In the file, there is reference to the arrest of a local drug dealer whose arrest was precipitated by a tip. Harry learns the source of the tip was his victim, suggesting the murder was in retaliation. It appears the Mexicans and Hawaiians are battling over the right to sell Black Ice.

Harry receives the autopsy report on Juan Doe from his on again, off again lover, Teresa Corazon. Teresa tells Harry that they found two different types of fruit flies on Juan Doe's body, suggesting that he was working at a place where the fruit flies are dyed and irradiated. Harry then asks Teresa about the autopsy on Moore, knowing as acting medical examiner that she performed it. Teresa confesses that she feels Moore was murdered based on evidence of a blow to the back of his head, but that deputy chief Irving is reluctant to allow her to call the death a homicide. Teresa asks Harry to keep this information to himself, but Harry calls a friend at the newspaper and leaks the information.

Harry begins investigating the fruit fly industry, discovering that fruit flies are transporter over the border from Mexico in special containers that are not searched at the border because of their sensitive nature. Harry begins to wonder if these containers might not be used to transport drugs over the border given the fact that a major drug lord operates out of Mexicali, the same town where one of these fruit fly companies is located. Harry's suspicions grow when he discovers his Juan Doe fits the description of a day laborer missing from Mexicali. Harry decides to visit Mexicali, but first he stops by Moore's apartment. Moore's widow told Harry that Moore grew up in Calexico and Mexicali and that he was obsessed with some things that happened in his childhood. Moore's widow also mentioned some photos of the past that Moore had. Harry finds these photos and takes a look at them, but finds nothing of relevance at this point.

When Harry arrives in Mexicali, he meets the cop who reported the Juan Doe missing and goes to the home of the Juan Doe to make an identification. The widow identifies the man as her husband. Harry then searches the man's home and finds paystubs from EnviroBreed, the fruit fly business Harry suspects plays a role in the Black Ice sales in Los Angeles. Harry then goes to EnviroBreed, but does not find any cooperation. At his hotel that night, someone takes a shot at Harry, telling him that he is getting close to finding a killer. Harry then breaks into EnviroBreed and finds a tunnel that appears to connect the business to a ranch belonging to drug lord Zorrillo across the street.

Harry sees a picture of Zorrillo and realizes that he is the same child he saw in some of Moore's pictures, making him suspect that he is Moore's half brother. Harry also visits the childhood home of Moore and learns that he obsessed over the house and was often seen watching it. Later, Harry is involved in a raid of Zorrillo's ranch. Harry goes into a tunnel to track a man who got away, a man Harry suspects is Zorrillo. The man gets away, but Harry sees a boot print that tells him that Zorrillo is dead, but Moore is still alive. Harry tracks Moore to his father's house and learns that Moore went to Zorrillo to ask for the money to buy his childhood home. In exchange, Moore was to turn a blind eye on his brother's drug trade in Los Angeles. Moore was not happy with the arrangement, however, so he killed Zorrillo to make it appear that he had killed himself so that he could escape the country. Moore then pulls a gun on Harry and forces him to shoot. Harry leaves the body in the abandoned house, hoping it will not be found until it is decomposed enough to hide Moore's identity, that way no one will ever know what Moore did and his widow will get his full pension.