Highly-trained Creationist ninja assassin travels back in time to take out Charles Darwin before he publishes “The Origin of Species.”
Loses his faith. Finds himself entangled in a homosexual love triangle with Darwin and Captain Robert FitzRoy of the HMS Beagle.
The highly-evolved 21st century germs he carried back in time with him (not on purpose) wipe out all life on the Galapagos Islands, including the crew of the ship, but he smuggles his lovers back to the present, after dosing them with antibiotics.
Potential sequel: “Charles Darwin Must Live”
When they come back to the present, they find that nothing has changed, really. Other Victorian scientists published the findings that, in our timeline, Darwin had been first to the post with.
The only change is that there’s an alternate version of the assassin himself, who never went back in time, and who is tasked with wiping out our main character and his lovers by the Creationist ninja leaders, who wish to cover up the botched plans of their other-timeline counterparts.
Hijinks ensue as the trio attempt to escape their pursuer while working through their own romantic complications.