Easier said than done. The qualities of time travel, as presented in literature and on screen, require logic. There's the famous Grandfather Conundrum as follows:
A young man goes back in time to kill his grandfather, a notorious (Fill in the blank: Serial Killer, Pedophile, Dictator). Does he succeed? He does, but only by killing his grandfather AFTER the time traveler's father was born. Otherwise?
No time traveler.
And, how many crimes had the grandfather committed BEFORE giving birth to the time traveler's father? How is the father affected by the "murder" of his father?
Not so with Time After Time, Karl Alexander's excellent novel adaptation to the screen is the proverbial clinic in quantum leaps. And BONUS, it is a great story with two capable leads in Malcolm McDowell as HG Wells, and Mary Steenburgen as Amy Robbins.
Steenburgen is the modern day character, a bank manager, in 1979 San Francisco, California. McDowell, as the famous author and scientist of late 1800s London, has yet to summon the courage to actually USE his time travel device. Seems Wells is also good friends with a Doctor John Leslie, or Jack-The-Ripper as he is known in police circles.
Leslie flees 1888 London, when the police close in after his latest prostitute butchering. He "borrows" Wells' time machine, and winds up in 1979 San Francisco, where he continues slaughtering women.
Wells has no choice.
He arrives in the City by the Bay, not yet turned into the socialist dystopia we know today, meets Amy Robbins, falls in love, and they live happily ever after.
Except for the knowledge of the new serial killer carving up part of the female population.
Wells once again finds his courage and sets out in pursuit of John Leslie, putting his own safety and that of Amy in jeopardy. The police don't buy his story, AND they think Wells might be the killer.
Along the cinematic pathway, the viewer is treated to a feminist seduction, a body hauled out of Stow Lake using a construction crane, plenty o' blood spatter, a case of mistaken identity which leads to a tasteful dismemberment, and a showdown at the California Academy of Sciences.
And zero opportunities for the viewer to shout, "Hey, wait a minute! Didn't Jack-The-Ripper just kill himself?"
Yes, no mistakes.
Youtube. It's a rental. Spend the money.