Sarah Jane is up to something. The kids get sick of her lying and sneaking around, so they follow her. Expecting something to do with aliens, they are shocked to see her on a date! Her boyfriend Peter Dalton soon pops the question. Clyde and Rani are naturally suspicious, and start investigating him. When they discover that his house is unlived in, Sarah Jane is unfazed. In fact, she's acting downright weird, waving off their suspicions and even deactivating Mr. Smith.
The day of the wedding arrives. Clyde smuggles K-9 into the chapel. Everything seems to be going smoothly... until the Tenth Doctor crashes the wedding!!
Turns out it's all a ploy by the Trickster, who gave a dying Peter a second chance at life and even love, in order to get Sarah Jane to forget about fighting aliens. The ring is a brainwashing device, and Sarah Jane's "I do" would have sealed the deal. The Trickster traps the Doctor, Luke, Rani, and Clyde Just One Second Out of Sync with the rest of the universe, and Sarah Jane and Peter Just One Second Out of Sync with them.
- Altar the Speed: Sarah Jane and Peter sure are in a rush to get married...
- Bad Liar: K9 is absolutely horrible at it.
- Bigger on the Inside: It's Clyde's turn to say it this time. Luke uses the term "dimensional trancendence" instead.
- Blatant Lies: "Do not look at me. Everything is normal." — K9
- Brainwashed: Sarah Jane, once again, in a nod to her tendency to get hypnotised in the classic series.
- Cartwright Curse: Poor Sarah Jane.
- Continuity Nod: Sarah Jane jokes about sending the Doctor's wedding invitation to Metebelis Three.
- Maria, Alan and the Brigadier are also mentioned, though sadly can't make it.
- The Novelization adds Yates, Benton, Harry, Clyde's mum, and Brendan and the Bakers from K-9 and Company to the couldn't make it list.
- The Doctor recognizes Luke from the previous crossover (see below).
- Once again it's revealed that Sarah Jane hates being called Sarah — but this episode reveals that it's because the Doctor is the only one allowed to call her by that name; it's reserved, specifically, for him.
- Crossover: This is the second time SJA has directly crossed over with its parent show. (At least when judged by airdate; the third crossover was filmed before this one, but aired after it.)
- Date Peepers: Luke, Rani, and Clyde.
- Deadpan Snarker/Vitriolic Best Buds: Mr Smith and K9, as always, show shades of this.
- Deal with the Devil: Peter does this, though in fairness, he thought it was a Bargain with Heaven.
- DecemberDecember Romance: Both Peter and Sarah Jane are getting on in years.
- Economy Cast: A rather tragic example with the wedding itself, which lacks the large crowd of extras and instead just has the regular cast, Rani's parents, Peter and the priest. A few handwaves are rattled off for why established characters don't appear - Maria has exams and her father is tied up at work, Clyde's mother is busy with a different wedding, the Brigadier is still in Peru note . The groom's side is not represented at all and, when asked by Clyde if he has any family, Peter replies "I'm afraid I'm the only one left. Last of the line."
- It's even lampshaded by Mrs Chandra who notes the few obscure acquaintances who do attend (Sarah Jane's hairdresser, Emma; her editor, Clerissa; her accountant, whose name Chandra cannot recall.), and snidely notes that this is inevitable when you hurry to get married.
- Fourth Date Marriage: Justified, for once.
- Genre Blind: Apparently, Peter didn't think anything of giving Sarah Jane a ring that controlled her mind. And the fact that "the angel" gave it to him doesn't seem to have clued him in at all.
- Gold Digger: Rani and Clyde suspect that Peter is one.
- A Good Name for a Rock Band: The Pantheon of Discord, according to Clyde. The Doctor agrees.
- Ham-to-Ham Combat: Ten has an enormous ability to show off... and the Trickster is an enormous ham. The two end up meeting.
- Heroic Sacrifice: Peter, who gives the Trickster a brief "The Reason You Suck" Speech.
- Incoming Ham: The Trickster, as usual. DOCTOR!
- Just One Second Out of Sync: The Doctor quotes this trope by name.
- Lame Excuse: Even K9 thinks Sarah Jane's excuses are pathetic.
- Large Ham: The Tenth Doctor turns up. Need we say more?
- Mind-Control Device: Sarah Jane's engagement ring. When things get just too weird, though, she has the willpower to take it off.
- Palette Swap: The Trickster invokes this, appearing in white instead of black to Peter.
- Parent with New Paramour: Unusually for this trope, Luke is enthusiastic about Sarah Jane's new beau, forbidding Clyde and Rani from ruining things.
- She Cleans Up Nicely: In a completely non-romantic example, this is Luke's response to Rani and Sarah Jane all dolled up for the wedding.
- Speak Now or Forever Hold Your Peace: Obviously. Done by the Doctor himself, of all party crashers.
- The Masquerade Will Kill Your Dating Life: Narrowly averted. Sarah Jane receives a package containing an alien life form at the same time Peter shows up at her house. Fortunately, Rani and Clyde are there to cover for her.
- The Trickster also plans for this trope to be inverted-Sarah Jane and Peter will be too busy with their wedded life to fight aliens, leaving Ealing wide open.
- Wedding Deadline: And the fate of Earth hangs in the balance.