The end of the world sounds pretty terrible, but turns out it's tolerable as long as David Tennant is there. The former Doctor Who star co-headlines Amazon's adaptation of Neil Gaiman and Terry Pratchett's novel Good Omens, and it's a good thing, because his demonic performance is the main, and close to only, reason to watch it.

Though it deals with the apocalypse, those familiar with the book know that Good Omens is absurdly silly, and Amazon's six-episode version doubles down on that by bringing the book's quirky sensibilities to life with special effects and playful presentation. Tennant plays the demon Crowley, a representative of Hell whose job is to watch over Earth, tempt humans into doing all sorts of bad things (Crowley was originally the Garden of Eden's serpent, so he knows how to do the job), and prepare things for the arrival of the Antichrist in order to kick off the war between Heaven and Hell, both of which desperately want the battle for Earth to commence because each side thinks it can win once and for all. Crowley is joined by the angel Aziraphale (Michael Sheen), who's essentially Crowley's opposite in every way; he performs miracles to even out Crowley's influence, and while Crowley is a sunglasses-wearing badass with attitude, Aziraphale is an uppity, cultured bookworm.

David Tennant, Michael Sheen; Good OmensDavid Tennant, Michael Sheen; Good Omens

Despite their differences, Crowley and Aziraphale have a deep respect for each other and are good pals, and their odd friendship forms the backbone of Good Omens. In fact, the two have such a good time together on our rock that they're not interested in the world coming to an end, so they conspire to postpone it as long as they can. They figure that if neither of them influences the Antichrist too much or if Aziraphale is able to counteract Crowley's influence, the apocalypse will be indefinitely delayed. And as bureaucratic as Hell and Heaven are portrayed to be (paperwork seems to be rampant in matters of good and evil), the hope is that both sides might eventually forget about the whole thing.

In keeping with Gaiman's extraordinary sense of imagination, their plan hits a snag when the Antichrist is switched at birth with another unexceptional boy, and he's effectively lost. That starts a search for Adam (as he was named by his British parents) by multiple parties, and Good Omens is off to the races.

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In keeping with Gaiman's questionable tendency to take an idea and blow it out to unnecessary confusion, Good Omens tells three stories simultaneously, two of which don't feature Tennant and are therefore on the boring side of things. In addition to Crowley and Aziraphale, one thread follows Adam (Sam Taylor Buck) and his friends as Adam slowly becomes absorbed with his powers, and another focuses on Anathema Device (Adria Arjona), the great-times-five granddaughter of a witch who wrote a book of prophecies, one of which accurately predicts much of this apocalypse mess, and Newton Pulsifer (Jack Whitehall), the descendant of the witch hunter who burned Anathema's witchy great-times-five grandmother.

Good Omens fades whenever Crowley and Aziraphale aren't on screen, which is about half of the time, unfortunately. A lot of that has to do with the show's characterization; rather than traditional character arcs involving change, progression, and personal obstacles, Good Omens' players are more straight lines as they're put in a situation and deal with it as they would. If character journeys are going to be this flat, they'd better be played by extraordinary talents (like Sheen and Tennant) or be interesting characters on their own (like Aziraphale and Crowley).

Jon Hamm, Good OmensJon Hamm, Good Omens

Instead, plot and voice-over narration (by Frances McDormand, playing the role of God) take up all the space in Good Omens, leaving Good Omens entertaining at times but mostly feeling hollow whenever viewers try to dig deeper into anything other than what's happening. In fact, the most emotional the series ever gets is during a 25-minute gag in Episode 3 that details the growth of Crowley and Aziraphale's relationship throughout the centuries, as we see the two cross paths during different time periods in history. It's the most the show focuses on character relationships, and unsurprisingly it's the most enjoyable part of Good Omens.

By the time Good Omens comes to its climax and the fate of the world is at risk, so many half-developed characters — played by fantastic actors such as Jon Hamm, Mireille Enos, and Nick Offerman — are gathered together but draw no real interest. The themes of good versus evil are barely scratched, which is odd given the content of the show, and the story ends in a hackneyed way, leaving you thinking about what could have been.

There is fun to be had, though. The insanity of the whole scenario allows for plenty of humor, and Good Omens fires off a relentless stream of corny special Who-vian effects that give it a playful and campy vibe (there's a chase scene that takes place between two entities traveling through telephone wires, for example). And I really can't say enough about David Tennant, who plays Crowley like he's Mick Jagger going through a goth phase, and Michael Sheen, whose positivity perfectly offsets what Crowley throws at him. They're pulling double duty by saving the world and the show from total disaster.

Good Omens premieres Friday, May 31 on Amazon.