The lives of a mother, Helen (Jessica Hynes) and her son Zach (Noah Valentine) are changed forever with the appearance of a kind stranger, Bob (Steve Pemberton).
Tropes
- Ambiguous Ending: The end of the episode has Bob and Rudolph in a Gun Struggle over a laser pistol, then shows the beginning of the episode again only to end before revealing if Rudolph managed to travel back in time or not.
- Ate His Gun: Bob does it in Zach's room after relaying his message.
- Bitch Slap: Helen delivers a slap like this to Zach after he calls her a bitch.
- Bratty Teenage Son: Zach is extremely uncooperative, rude, and generally unpleasant to Helen, calling her a bitch at one point.
- Calculator Spelling: The man from the future assumes the name "Bob" which he took from the upside-down barcode digits 909 he found on a cereal box.
- Chekhov's Skill: Zach's A-levels are in maths, physics, and chemistry. Physics becomes important to his chosen career path, while chemistry becomes important to his other potential career path as he apparently uses it to find a potential cure for Helen's cancer.
- Daddy Didn't Show: According to what Helen says, Zach's father, who is in Singapore, has a tendency not to show up.
- Distant Epilogue: The final ten minutes of the episode (before the rewind) is set in the same house some forty to fifty years later.
- Distinguishing Mark: Bob identifies himself as the older Zach with the tattoo that they both have, which might make it a downplayed version of Storyboard Body.
- Embarrassing Cover Up: When Zach asks why Helen has been calling the hospital, she doesn't want him to know the truth (that she is awaiting the result of a test for cancer) so tells him it was about cervical screening.
- Extremely Protective Child: If Zach finds out the truth about Helen's illness before it's too late, he dedicates himself to finding a cure (and succeeds).
- Foreshadowing: Bob's revulsion when Helen is hitting on him. She simply assumes he's turning her down, but it's because he knows (and she doesn't) that it would be Surprise Incest, since he's her son.
- Gun Struggle: Bob and Rudolph in the future fight over a laser gun in the kitchen which makes the coffee cup in the present tip over.
- Kick the Dog: When Bob/Zach points out that his mother will die of cancer if Rudolph succeeds in going back in time, Rudolph simply replies "Fuck her".
- Line-of-Sight Alias: Bob's name turns out to have been taken from the back of a cereal box, which Helen finds out after he leaves the first time.
- Match Cut: In the opening scene, a closeup of a spinning skateboard wheel to stirred coffee in a cup.
- My Future Self and Me: Bob uses a time machine to return to his young self and warn him about his mother's death.
- Secretly Dying: Helen doesn't tell Zach that she has cancer, which will kill her in a short time. Whether or not he ever finds out depends on Bob's actions.
- Struggling Single Mother: Helen and Zach are estranged following her divorce, despite her best efforts.
- Time-Shifted Actor: Pemberton's Bob turns out to be one for Zach.
- Title Drop: Bob delivers one while telling Zach that Helen is dying.
- The Topic of Cancer: Helen turns out to have terminal cancer, leading Bob to regret that he wasn't kinder to her when she was still alive.
- Totally Radical: The mother tries to cut the ice with her son by trying to speak his language and fails.Helen: Let's cut the beef, bro.Zach: No-one says "beef" anymore.
- Verbal Tic: Bob repeats the double letters in any word that has them.
