Roots: There are references to Alka-Seltzer, Knight Rider, Prince, Hitler, Tigger, Mars Bars, and Jack and the Beanstalk.
Goofs: The TARDIS console is described as being five-sided [a quirk of the architectural configuration?].
Continuity: The Thannos system contains fifty-three planets and was named after the word Thenossus, from the old tongue of the humanoid inhabitants of the Inner Worlds. Thenossus means "bead tapestry". Thannos may also be the name of the homeworld. The inhabitants of the Thannos system are humanoid but apparently human: the men have long eyelashes, whilst the women have no eyelashes, inner eyelids, and two tongues. The Outer Planets are gradually being terraformed to the objections of the indigenous populations. The inhabitants of the Outer Planets are known as Outers and are oppressed by the Thannos Multiplanetary Government, which rules the system, resulting in rebellion. The waste from the terraforming is dumped on Hirath. Hirath is located in the Thannos system. It appears pink from space. The planet has several moons. The relative year is 3177 [approximately 2202 - see Legacy of the Dalek and Dreamstone Moon]. The planet's surface is divided into different time fields. Temporal Commercial Concerns owns the planet and rents out different time zones to clients who want to hide people or secrets there. Clients include the Thannos Multiplanetary Government, plus the governments of planets from outside the system. Both TCC and the moon base that controls Hirath are of Kusk origin, but nobody in the Thannos systems knows which aliens are responsible. The moon base is actually a Kusk spacecraft that crashed or was buried on Hirath's moon. At least one zone is used as a prison. Another is used as an insane asylum where inmates are used for experiments in biological enhancement. Most of the planet's surface is covered in mudflats, sand and rock. There are birds native to Hirath. Other planets in the Thannos system include Venel and Ipmuss.
The Kusks are eight-foot tall humanoids with sticky, brown, lumpy skin, orange eyes and massive bony heads with downward pointing spiky ears. Their tongues are white. They have six fingers on each hand. Their thighs are fat and wide and covered in a sweaty liquid that pours from their midriffs, and they have thick, tuberous, muscular upper arms. They have huge club feet which exude amber gum. A bony ridge of muscle runs across the tops of their chests from shoulder to shoulder. Due to the harsh atmospheric conditions of their home planet, their lungs have an unusual filtration system and they exhale obnoxious fumes. They wear plastic loincloths. They call Hirath AB455, and its first moon AB456. Their ships are partially organic, with a metal framework. They don't appear to have individual names, just ranks including Leader. Kusks under combat duty wear yellow sashes. The Kusks have highly advanced computer technology and discovered the maenus chip during the stellar war that devastated their home planet Kuskas. Kuskas was the only planet orbiting its sun and was used as a tactical front in the war, which was fought by two unknown alien species: the cities of Kuskas were destroyed in the crossfire and the Kusks almost wiped out. They have been rebuilding ever since and have developed limited time travel technology. They built a temporal probe which crashed on Hirath, creating the mass of conflicting time fields that cover the planet. The probe was designed to collect strategic data from throughout history and analyse it.
The Doctor's Volkswagen Beetle is protected by a force field. When the Doctor was young, his tutor, whom he describes as "the most attractive person I've ever met", told him "the universe is nothing but a functional chain of causality at every level, governed by the oldest and simplest laws". The Doctor replied that however much people try to take the mystery out of things, they cannot diminish wonder, beauty and discovery. He sings a Venusian lullaby (see The Curse of Peladon, The Monster of Peladon, Venusian Lullaby). He is largely immune to the conflicting time fields on Hirath. He is forced to leave Hirath's moon without Sam.
Sam is still seventeen years old. She tried drugs once but the experience frightened her. As well as being a vegetarian, she also abstains from caffeine. Whilst playing kiss and chase with Peter Stokely in the playground on 3 June 1989, she fell and skinned her knees when he dropped a ball in front of her. Believing the injured Doctor to be dead, she is rescued from Hirath's moon by Anstaar, who drags her into the Kusk ship, which takes off on autopilot: she is thus unable to return to the TARDIS and is separated from the TARDIS.
Around the central console in the TARDIS are clocks, candles, ornate antique chairs, piles of discarded books, and an occasional table with binoculars, a telescope, and some opera glasses. There is a bronze effigy of a humanoid figure against one wall of the control room, with an optician's eye chart hung around its neck. There is a row of filing cabinets containing first edition Dickenses, unfinished Alpha Centaurian poetry, and Lego bricks.
Links: Sam recalls the Daleks (War of the Daleks) and the Krotons (Alien Bodies). The Doctor mentions the Brigadier. Time Trees grow on Hirath (Genocide). Sam's departure in a Kusk ship leads into Legacy of the Dalek and Dreamstone Moon.
Location: Hirath, and one of its moons [c.2202 according to Seeing I].
Future History: The K'Arme is the Justice Control Force from the homeworld, which controls the police force in the Thannos system.
The Bottom Line: Remorseless but dull, Longest Day boasts monsters and temporal catastrophe with lashings of horror, but fails to make an impact. The Kusks are one-dimensional, the humanoid characters forgettable, and the novel's only real significance lies in the separation of the Doctor and Sam at the end.