The Ghost Squad books are a young adult series of books by E.W. Hildick. They follow the eponymous Ghost Squad, which consists of four ghosts: Danny Green, Carlos Gomez, Joe Armstrong, and Karen Hansen, and their two living friends: Wacko Williams and Buzz Phillips. Able to communicate with their two living friends, the four ghosts investigate crimes by using their abilities as ghosts. Complicating matters are that the ghosts cannot actually pass through walls, can barely affect affect physical objects, and have a limited store of energy to do that. If they exhaust themselves, they fall into a deep slumber, and might fade away.
The series consisted of six books:
- The Ghost Squad Breaks Through - The four ghosts find each other, and learn that one of them can communicate with the living, which leads to them banding together to foil a jewelry store robbery with deadly consequences...
- The Ghost Squad Flies Concorde - When Danny's mother is targeted by a scammer, the Ghost Squad has to fly to London to discover what his plan is, and it has to do with the disappearance of two children, who seem to be haunting one of the conspirators. Meanwhile, they learn that there are older, more powerful, ghosts out there...
- The Ghost Squad And The Halloween Conspiracy - The Ghost Squad learns that a senator's stepson plans to sabotage his stepfather's distribution of Halloween candy with potentially deadly results. The Ghost Squad must not only solve the mystery, but also convince the Senator, and deal with a malevolent ghost looking for revenge against them for his death...
- The Ghost Squad and the Ghoul of Grünberg - A stranger is surveilling the living members of the Ghost Squad. Their investigations lead them to a computer camp with a missing camper, and then an international hunt for a Nazi war criminal with the sobriquet of the Ghoul of Grünberg...
- The Ghost Squad and the Prowling Hermits - It's Christmas, but the Ghost Squad must deal with the sinister machinations of Dr. Purcell, who controls "hermit" ghosts who can possess the living. Joe chooses to infiltrate, but what will happen when he is found out?
- The Ghost Squad and the Menace of the Malevs - The Ghost Squad investigates a man who was the instrument of one of their deaths. Far from an isolated incident, he's had a steady campaign of deadly "accidents" and it doesn't look like he plans to stop. Complicating things, the Ghost Squad confronts a superghost, who is able to possess not just the living, but other ghosts...
This book series incorporates the following tropes:
- Jacob Marley Apparel: All of the ghosts are dressed in the clothes they died in, albeit untouched by the manner of their death.
- Gold Digger: When investigating a suitor to Danny's mother, they quickly learn that he is after her for the settlement she's receiving for Danny's death, but also that there is something considerably more sinister going on.
- Our Ghosts Are Different:
"There were great chunks missing: in the thighs, especially the left one, and the torso, where it seemed that the whole of the right lung and rib cage had been torn away or, rather, bitten away by some monster with huge jaws. And what made the sight even more horrifying was that these weren't simply wounds, however ghastly. There were no frayed and ragged edges of cloth and flesh, no splintered bones, no blood stains. Like all ghosts everywhere and in all ages, the mans' clothes and body didn't bear the marks of what had actually killed him .... No. The edges were smooth."
- These ghosts cannot move through physical objects or people, and feel extreme discomfort if forced to.
- The ghosts are not tied in any way to the place where they died, or even to their family. However, if they lose their purpose, they fade away.
- While they can affect the world in small ways, such as gathering insects to them, applying a small physical force, or, like Carlos, able to manipulate fine details of electronics, they can only exert so much effort before they are forced into a deep sleep, during which some ghosts fade away.
- Some humans "sleepwalk" with their souls leaving their bodies, but being relatively insensate to the world.
- While they do not have psychic powers, the ghosts are unhampered by mortal concerns such as heat or cold, or a need to breathe, so they are excellent observers of small physical cues as to whether a person is lying or telling the truth.
- Over time, while ghosts maintain their mental identities, ghosts who've been around for a long time experience a degradation of their form, even as they grow more powerful in their ability to affect the world. One ghost in London, who is over two hundred years old, is missing pieces.
- Suicide Attack: In the second book, The Ghost Squad Flies Concorde, they have to foil one of these, a man who plans to board the Concorde with a bomb in his stomach, set to explode when they reach altitude.
- Unfinished Business: Ghosts are only tied to the world by the things they left unfinished. Danny wants to watch over his mother, who is bereft by his death. Joe was the victim of a murder, and worries about his young wife. Karen is held by the grief of her father, who feels responsible for her death because she was running an errand for him. Carlos... well, actually his family is doing fine, and it was an accidental death, but he really wants to finish that project he was working on when it killed him... One thing which is a firm rule, as best they can tell, is that suicides never become ghosts.
- "Malevs" are a degenerate case where the motivation of the ghost is simply to cause pain to the living and to other ghosts.
- The "Mad Ones", or "Elementals", has suffered The Fog of Ages and barely retain their humanity, holding on to their original Unfinished Business to the point where that is what defines them.