Holmes: "Careful observation and perceptive thought: eyes and brains."
Watson retains the job of the opening narration, though now in a metallic voice.
Lestrade drives Holmes and robo!Watson to the Reichenbach Falls to see the place where Holmes buried Professor Moriarty in 1891. Holmes makes a quip at Lestrade's driving and catches sight of a large pine tree which, in a flashback, saved his life two centuries ago. Remember, the opening of the previous episode showed Moriarty and Holmes going over the edge. Holmes somehow managed to grab hold of a sapling (which somehow managed to hold two tall men's weight). Holmes was holding Moriarty's hand, but they could not keep their grip on each other, and Moriarty fell.
Back in the 22nd century, Lestrade lands at an ice cave near the Falls. Inside the cave, the trio meets the spectacle of Professor Moriarty's corpse, perfectly preserved in ice. Lestrade is aghast. If that's Moriarty, then who is the man running around New London with his face? Holmes even says that the man had no descendants.
A cave-in promptly occurs, sending our heroes back outside. (It's the first and unfortunately not the last time that Holmes will make some cry of alarm that does not at all sync with the action.) Professor Moriarty is now buried forever.
They return to New London to find that the crime wave mentioned in the previous episode is getting way out of hand. Worse still, people who previously had no criminal records are suddenly committing robberies. New London-wide. Holmes sets off to investigate, and Chief Inspector Grayson reluctantly allows Lestrade to join him. Holmes offhandedly remarks that the robot tag along. This casual attitude (displayed throughout the episode and heightened to annoyance) will come back to bite him later.
- Call-Back: Watson is shot in the leg, but, being a robot, he's able to shrug it off. Holmes has a brief moment of panic, however - a nice little nod to the famous "You're not hurt, Watson? For God's sake, say you're not hurt!" scene of "The Adventure of the Three Garridebs".
- Curb-Stomp Battle: Those thugs never stood a chance against Lestrade. Interesting, though, that we never see her fight that well again.
- Disney Death: Watson gets a very brief one, just long enough for Holmes to well and truly panic and be very relieved and accepting of Watson when he comes out of the Thames.
- Drives Like Crazy: Averted. One of the very few times Lestrade is behind the wheel without driving like a speed demon. Still, her driving style is lampshaded by Holmes making a good-humored quip.
- Foreshadowing: The Professor's perfectly-preserved body. Now where have we seen this before? ...This will be very important in the next episode.
- Just a Machine: How Holmes regards robo!Watson throughout the episode, openly rebuffing him once when Watson refers to both of them as being "gentlemen".
- Kick Chick: Lestrade.
- Large Ham: Fenwick's hamminess is established when he catches the heroes.
- Laser Blade: Three punk criminals attack Lestrade with lightsabers, she beats the living daylights out of them, and we never see anybody wielding lightsabers again.
- Latex Perfection: Watson's elastomask, which actually shocks Sherlock Holmes speechless.
- Save the Villain: Holmes tells Moriarty to "Ho-old on!" when they're hanging from the sapling in his flashback of Reichenbach. Moriarty looks scared, too. But they can't keep their grip on each other, and Moriarty falls to his death.
- Sour Supporter: Grayson. Grayson, Grayson, Grayson.
- Suggested by...: The opening titles state that the episode is based on The Valley of Fear. However, there is no tangible connection, aside from Holmes, Watson, and Moriarty being involved in both.
- ¡Three Amigos!: Wiggins, Deidre, and Tennyson.