Timeless has always, more than any other time travel television series, explored the disruptive impact of trying to protect the past, not just on the present in general but on families in the present, the families of our time travelers in particular. In Lucy's case, the very first trip to the past erases her sister in the present, but helps her mother (who, not being a party to Lucy's time travel, has no memory of the lost sister). Flynn and Wyatt struggle in vain to keep their loved ones from perishing.
The main villain, Rittenhouse, is the subject of Flynn's attempt to save his family. But he's a villain, too - or, at least, someone with fewer moral qualms than Lucy, Wyatt, and Rufus. In past episodes, Flynn fights with our heroes in an unsuccessful attempt to nip Rittenhouse in the bud, by killing the founder in Revolutionary War times. That story was, in effect, a grandfather paradox tale, though there was no grandfather of Lucy or any of our characters literally involved.
Tonight, we get just that, and done up with all the trimmings. Flynn wants to kill Lucy's grandfather at a Rittenhouse meeting in 1954. He's not happy about the likelihood of this deleting Lucy, but he won't let anything stand in the way of saving his family. Lucy has a better idea, and she succeeds. (Or so we think.)
Along the way, we get a good little Joe McCarthy story (the episode is titled "The Red Scare," and as a nice touch Jiya gets a dangerous red eye condition), as well as a story about the difficulty of being gay in the 1950s (Lucy's grandfather, though happily married and already the father of a child - Lucy's father - is gay.) Rufus and Jiya finally get together, Mason turns out to have heart as well as a brain, and--
Well, I won't tell you the surprises at the end, in case you've read this far and somehow haven't seen the episode. But I will say there's more than enough here for a strong second season - a lot more to explore in the provocative intersection of family life and changes in time with erudite historical details that Timeless does so well. I'll be waiting...
See also Timeless 1.1: Threading the Needle ... Timeless 1.2: Small Change, Big Payoffs ... Timeless 1.3: Judith Campbell ... Timeless 1.4: Skyfall and Weapon of Choice ... Timeless 1.5: and Quantum Leap ... Timeless 1.6: Watergate and Rittenhouse ... Timeless 1.7: Stranded! ... Timeless 1.8: Time and Space ... Timeless 1.9: The Kiss and The Key ... Timeless 1.10: The End in the Middle ... Timeless 1.11: Edison, Ford, Morgan, Houdini, and Holmes (No, Not Sherlock)! ... Timeless 1.12: Incandescent West ... Timeless 1.13: Meeting, Mating, and Predictability ... Timeless 1.14: Paris in the 20s ... Timeless 1.15: Touched!