Well, if there were one inconsistency between this and the last episode, no one this time around expresses the notion that Sherlock and John maintain romantic notions toward each other, in fact, multiple characters remarking, for a differing change of pace, that John seeks female companionship.
Sherlock Holmes (Benedict Cumberbatch) and Doctor John Watson's (Martin Freeman) Landlady, Mrs. Hudson (Una Stubbs), returns, after being informed of John's orientation the last time around, and Molly Hooper (Loo Brealey) returns to the Police Mortuary, also realizing John's eye for the ladies, but so do new characters, as well.
In the absence of Inspector Lestrade (Rupert Graves), who does not appear in this episode, Detective Inspector Dimmock (Paul Chequer) substitutes for him, leading the Police investigation of a London murder spree bearing a connection to a Chinese syndicate's smuggling operation.
This begins at National Antiques Museum's Restoration Room, at which Chinese native Soo Lin Yao (Gemma Chan) specializes in preserving ancient ceramic tea pots, while British co-worker Andy Galbraith (Al Weaver) invites her to socialize at a pub after hours, but she turns him down. Soon, after someone wearing a sheet frightens her in the Museum after hours, Soo Lin Yao ends up missing, and Andy attempts to track her down.
Meanwhile, John experiences difficulties attempting to purchase provisions at an automated store, as the electronic cashier indicates that his banking card has insufficient funds. Upon his return to the flat, John discovers that Sherlock has turned down a case from lack of interest, but the bills amass, causing John to decide that he needs a job, but in the meantime, he asks Sherlock for a loan, so Sherlock says that he needs to go to the bank.
Bank Receptionist Amanda (Olivia Poulet) directs Sherlock and John to Sherlock's former university classmate, Sebastian "Seb" Wilkes (Bertie Carvel), who explains that someone broke into the fully automated bank last night to smear paint upon portrait; therefore, there's a hole in security. Seb offers Sherlock a five-thousand pound check to investigate.
Sherlock and John visit banker Eddie Van Coon (Daniel Percival), Sherlock entering his building through Miss Wintle's, Eddie's upstairs neighbor, apartment, climbing from her balcony to admit him to investigate, but in the process, Sherlock discovers a body, while keeping John waiting in the hallway.
Detective Inspector Dimmock expresses little patience for Sherlock as they conduct the investigation. But soon, Journalist Brian Lukis (Howard Coggins) runs through the streets as someone follows him into his flat, where a second body is discovered, leading Sherlock to deduce that the intruder could walk through walls of another locked room.
Back at National Antiques Museum, Andy discovers that Soo Lin resigns from museum, and he cannot locate her, while John approaches amicable Receptionist Sarah (Zoe Telford) at a Surgery Center, where he applies for a position for which he's over-qualified, which John accepts but continues to investigate with Sherlock all night, draining his stamina for work, while Sherlock must discover a link to connects the two murders.
At a library where a victim checked out books, John discovers a yellow graffiti design on bookshelf, matching discovery on bank portrait, so Sherlock consults Raz (Jack Bence), a graffiti artist, leaving John holding the can, and now he must face police charges.
At Lucky Cat Tea Room, Sherlock discovers a Chinese connection between murders and breaks into Soo Lin Yao's flat, where Sherlock is attacked by a strangler, while John waits outside for admittance. Andy then explains the tea ceremony demonstration, before yellow graffiti is found on a Museum statue.
Dimmock reaches Sherlock and John in search of Soo Lin Yao, to find yellow Graffiti paint on mural by railroad tracks, this to communicate with underworld. And back at Antiques Museum, Sherlock discovers that not every pot shines the next day.
Soo Lin Yao is soon discovered at Museum, explaining that the Cypher is after her, with the Mark of the Tong, an ancient crime syndicate, because when she was orphaned at fifteen, Black Lotus Syndicate forced her into smuggling into Hong Kong. Now, with a new life in England for the past five years, they search for her. She explains the identity of Black Lotus and the code of the graffiti, before a third body turns up at the Museum.
At the Morgue, Sherlock discovers that both male victims have the same tattoo mark on heel of right foot. Sherlock and John examine every book from two victims' collections through the night.
John invites Sarah to Chinese circus, where Sherlock joins them because he senses this a front of international smugglers. While Chinese Bird Spider performs, Sherlock discovers yellow spray paint in dressing room and is attacked by a Mark of the Tong, before Sarah joins forces to defend John and Sherlock.
When Sherlock searches for a Book which everyone would own, John is attacked, and John and Sarah kidnapped, taken to tunnel, and tortured for Empress Pin, while abductors do not believe a binded John is not Sherlock, as sands pour from overhead bag to lower large weight toward a binded Sarah. But will Sherlock be able to crack the secret code in time to figure whodunit and to rescue Sarah and John from the underground Chinese torture tunnel before the sands of time pour out, and additional bodies begin to surface?
Sherlock Holmes (Benedict Cumberbatch) and Doctor John Watson's (Martin Freeman) Landlady, Mrs. Hudson (Una Stubbs), returns, after being informed of John's orientation the last time around, and Molly Hooper (Loo Brealey) returns to the Police Mortuary, also realizing John's eye for the ladies, but so do new characters, as well.
In the absence of Inspector Lestrade (Rupert Graves), who does not appear in this episode, Detective Inspector Dimmock (Paul Chequer) substitutes for him, leading the Police investigation of a London murder spree bearing a connection to a Chinese syndicate's smuggling operation.
This begins at National Antiques Museum's Restoration Room, at which Chinese native Soo Lin Yao (Gemma Chan) specializes in preserving ancient ceramic tea pots, while British co-worker Andy Galbraith (Al Weaver) invites her to socialize at a pub after hours, but she turns him down. Soon, after someone wearing a sheet frightens her in the Museum after hours, Soo Lin Yao ends up missing, and Andy attempts to track her down.
Meanwhile, John experiences difficulties attempting to purchase provisions at an automated store, as the electronic cashier indicates that his banking card has insufficient funds. Upon his return to the flat, John discovers that Sherlock has turned down a case from lack of interest, but the bills amass, causing John to decide that he needs a job, but in the meantime, he asks Sherlock for a loan, so Sherlock says that he needs to go to the bank.
Bank Receptionist Amanda (Olivia Poulet) directs Sherlock and John to Sherlock's former university classmate, Sebastian "Seb" Wilkes (Bertie Carvel), who explains that someone broke into the fully automated bank last night to smear paint upon portrait; therefore, there's a hole in security. Seb offers Sherlock a five-thousand pound check to investigate.
Sherlock and John visit banker Eddie Van Coon (Daniel Percival), Sherlock entering his building through Miss Wintle's, Eddie's upstairs neighbor, apartment, climbing from her balcony to admit him to investigate, but in the process, Sherlock discovers a body, while keeping John waiting in the hallway.
Detective Inspector Dimmock expresses little patience for Sherlock as they conduct the investigation. But soon, Journalist Brian Lukis (Howard Coggins) runs through the streets as someone follows him into his flat, where a second body is discovered, leading Sherlock to deduce that the intruder could walk through walls of another locked room.
Back at National Antiques Museum, Andy discovers that Soo Lin resigns from museum, and he cannot locate her, while John approaches amicable Receptionist Sarah (Zoe Telford) at a Surgery Center, where he applies for a position for which he's over-qualified, which John accepts but continues to investigate with Sherlock all night, draining his stamina for work, while Sherlock must discover a link to connects the two murders.
At a library where a victim checked out books, John discovers a yellow graffiti design on bookshelf, matching discovery on bank portrait, so Sherlock consults Raz (Jack Bence), a graffiti artist, leaving John holding the can, and now he must face police charges.
At Lucky Cat Tea Room, Sherlock discovers a Chinese connection between murders and breaks into Soo Lin Yao's flat, where Sherlock is attacked by a strangler, while John waits outside for admittance. Andy then explains the tea ceremony demonstration, before yellow graffiti is found on a Museum statue.
Dimmock reaches Sherlock and John in search of Soo Lin Yao, to find yellow Graffiti paint on mural by railroad tracks, this to communicate with underworld. And back at Antiques Museum, Sherlock discovers that not every pot shines the next day.
Soo Lin Yao is soon discovered at Museum, explaining that the Cypher is after her, with the Mark of the Tong, an ancient crime syndicate, because when she was orphaned at fifteen, Black Lotus Syndicate forced her into smuggling into Hong Kong. Now, with a new life in England for the past five years, they search for her. She explains the identity of Black Lotus and the code of the graffiti, before a third body turns up at the Museum.
At the Morgue, Sherlock discovers that both male victims have the same tattoo mark on heel of right foot. Sherlock and John examine every book from two victims' collections through the night.
John invites Sarah to Chinese circus, where Sherlock joins them because he senses this a front of international smugglers. While Chinese Bird Spider performs, Sherlock discovers yellow spray paint in dressing room and is attacked by a Mark of the Tong, before Sarah joins forces to defend John and Sherlock.
When Sherlock searches for a Book which everyone would own, John is attacked, and John and Sarah kidnapped, taken to tunnel, and tortured for Empress Pin, while abductors do not believe a binded John is not Sherlock, as sands pour from overhead bag to lower large weight toward a binded Sarah. But will Sherlock be able to crack the secret code in time to figure whodunit and to rescue Sarah and John from the underground Chinese torture tunnel before the sands of time pour out, and additional bodies begin to surface?