Notorious but better-than-it-sounds [[SciFi science fiction]] novel by the equally notorious [[Creator/JackChalker Jack L. Chalker]]. It posits a world in which TimeTravel to or from the past is possible by [[MentalTimeTravel "leaping"]] into the body of a person of that time. There is a catch: spend too much time in the past, and you'll 'trip' and be stuck as that person permanently, even if you return to the present.

When the hero's first leap into the past uncovers a full-fledged war for control of the future, things go from bad to worse very, very quickly.

Predates ''Series/QuantumLeap'' by more than a decade.
----
!!Tropes:

* AuthorAppeal: It is Chalker, after all.
* BrotherSisterIncest: Guess what happens when you grow up on a desert island with no one but your parents and siblings for company?
* ButterflyEffect: Subverted: you have to kill someone really important before they'd accomplished their life's work to significantly affect the outcome of history. If you killed someone in the Middle Ages who was an ancestor of, say, Teddy Roosevelt, there'd still be enough genes in the pool for someone to give birth to Teddy Roosevelt hundreds of years later. History is like a big river and it "flows" around small impediments.
* DifferentForGirls: Specifically averted by TheMindIsAPlaythingOfTheBody.
* TheDragon: Eric Benoni. He'd be the BigBad but he works for a BiggerBad in the form of a Politburo-style committee.
* ForWantOfANail: The protagonist turns out to be the nail. [[spoiler: He's the mother of TheDragon]]. And it's implied that other time travel experiments also "failed" because their subjects were forcibly recruited into the time war by future time travelers.
* EvenBadMenLoveTheirMamas: Eric again
* GenderBender: Several, as you don't get to pick your target when you travel to the past.
* TheGreatPoliticsMessUp: referenced as the antagonists are largely the inheritors of the old Communist block nations, who inherited the Earth by the simple expedient of waiting for the Capitalists to leave through planetary colonization. TheDragon, who has been given a relatively free hand in the time war, amuses himself by targeting Marx for a historical disruption.
* HitlersTimeTravelExemptionAct: Played with, though the historical figure in question turns out to be Karl Marx instead of Adolf Hitler.
* InSpiteOfANail: Played with: Killing Karl Marx before he publishes ''Das Kapital'' has a big effect on the time stream, killing him after not so much, and killing him shortly before he would have died anyway has hardly any affect at all.
* MeaningfulName: Eric claims his ''nom de guerre'' "Benoni" means "son of my sorrow" in Hebrew.
* MentalTimeTravel: in effect but possibly not reality: OntologicalInertia causes each time traveler's personality to get inserted into a person of that time period. Whether or not that person actually existed prior to the time traveller's arrival is never made clear.
* NoOntologicalInertia: Subverted. "Nightsiding" people (cutting them off from their prior selves) does not make them disappear or eliminate what they have done, but it does make them vulnerable to OntologicalInertia
* OntologicalInertia: Played with. Time does its level best to shunt time jumpers into insignificant people who can't or won't affect the timestream. And if you get nightsided, watch out, because time does not like loose ends.
* RetGone: The goal of the war is to do this to the enemy.
* RippleEffectProofMemory: Subverted: you lose some of yourself (and gain some of the personality of your new host) every time you 'trip'. And if you spend too much time in the host's era afterwards you'll be totally assimilated. The heroes use an entire supercomputer just to keep track of the temporal logistics to prevent this from happening to their troops, and it means some people can't go on some missions because they'll exceed their exposure time.
* DisappearedDad: The driving force behind the Dragon.
* PlaceBeyondTime: Not really, but the heroes' base is in the early Cenozoic, far enough back so plate tectonics will destroy all of the evidence.
* SanDimasTime: The "edge" in the future is always moving. [[spoiler: The entire plot turns out to be a huge scheme to extend the edge long enough for people in the future to disarm the bombs their enemies had set as a booby trap. The huge, convoluted stable time loop was merely a distraction to give the people at the edge time to work.]]
* SciFi: a prominent example
* ScrewYourself: And have lots of children doing it, [[spoiler: though by the point Dawn hooks up with her prior self Ron she'd tripped over as a woman several times and her earlier incarnation as Ron seemed less like a prior self than a fantasy lover.]]
* SetRightWhatOnceWentWrong: Played against MakeWrongWhatOnceWentRight as each side in the time war monkeys with past events to gain momentary advantage in the future. A time agent might be ordered to kill Karl Marx on one mission only to get tasked with saving him later (later meaning some future point in the agent's own subjective history.) The protagonists are primarily distinguished from the antagonists in that they are reluctant to take the second course, though "wrong" and "right" are often subjective.
* SelfMadeOrphan: Combined with TrulySingleParent and EvenBadMenLoveTheirMamas in a way that only a TimeyWimeyBall makes possible. Eric Benoni joined the antagonists because the protagonists sent his father Ron on a mission from which he never returned, not knowing (thanks to SanDimasTime) that Eric himself would be the antagonist who prevented his own father from returning, sending Ron on the stable time loop where he met [[spoiler: and became]] Eric's mother Dawn instead. So Eric actually enabled his own birth and his own StartOfDarkness in one twofer.
* StableTimeLoop: Used to "nightside" people by cutting them off from their prior selves.
* StartOfDarkness: Eric Benoni started as the eldest child of protagonists Ron and Dawn [[spoiler:(who are actually the same person, thanks to the story's combination of StableTimeLoop and GenderBender, though neither Eric nor Ron were told that particular detail about his parentage)]] joined the antagonists because he blames the protagonists for the loss of his father. Subverted later when he captures Ron on a mission and learns that ''he's'' the reason his father never returned, making his StartOfDarkness self-inflicted.
* TakeAThirdOption: The protagonists eliminate TheDragon through the simple expedient of reuniting his familuy before his StartOfDarkness, severing that particular StableTimeLoop and nightsiding him.
* TemporalParadox: Several. Both sides are either trying to cause them if they benefit themselves or smooth them out if they benefit the enemy
* TimeMachine: several variations and upgrades, from primitive "time suits" to more sophisticated belts and wristbands.
* TimeyWimeyBall: And how. {{Justified|Trope}} -- the rules of time travel ''appear'' to change around, but that's only because it's so poorly understood that nobody knows what the rules actually are. Combine this with improvements to the process and the technology, and things look especially inconsistent. That said, it still looks like a continuity snarl to the agents living through it because all of the intersecting time loops mean they often don't encounter the enemy, their fellow agents or even themselves in strict chronological order. Your next encounter might be in their subjective past, and thanks to "tripping" they might not be the same race or gender the next time you encounter them. One such incident resulted in Eric inadvertently nightsiding his own father [[spoiler: who returned after several "trips" to become Eric's mother.]]
* TimePolice: The hero is forcibly recruited.
* TrulySingleParent: Using a GenderBender and a StableTimeLoop followed by ScrewYourself instead of cloning, but still...
* UnfortunateNames: Ron Moosic, the Hero. His grandfather, an immigrant with an unpronounceable name, renamed himself after the Pennsylvania city. IT proved an unfortunate choice.
* TheWarOfEarthlyAggression: The time war proves to be a second front.
* UsedToBeASweetKid: TheDragon used to be the hero's eldest son--something neither of them is particularly thrilled to learn.
* WordOfGod: Chalker claimed that he wrote this story in an attempt to address the questions raised -- [[TakeThat but not answered]] -- by Creator/RobertAHeinlein's ''Literature/AllYouZombies''.
* YouAlreadyChangedThePast: Used, averted, and subverted as the hero experiences several time loops from various perspectives. Shows up initially when the protagonist learns that ''he'' is from the past and the real leading edge of time is hundreds of years in ''his'' future.
* XanatosGambit: The protagonists are playing for time, and even gave TheDragon his StartOfDarkness because they knew he'd extend the war,
----