Series 1, Episode 1: Stochastic Dominance

2005: Sabine Moriarty's estranged brother, Jim, uses the 7/7 attacks as an pretext to reconnect. She reluctantly agrees to meet him, hoping that in the years of their separation he has recanted his criminal ways and turned over a new leaf. He hasn't. He has a new project, and wants her help— to be the undoing of Sherlock Holmes.

In the 1970s, young Jim tries to send his sister to a magical land.

Series 1, Episode 2: Long Range Forces and Broken Symmetries

In the wake of the arsons, Sabine tries to derail Jim's attempt to frame Sherlock Holmes.

Back in the 1970s, young Jim shows Sabine what adults do.

Series 1, Episode 3: A Sum Over Histories

Sherlock and John chase down the latest murders. Sabine tells her old math friend Aidan about a remarkable new theorem. After Jim lets Sabine see where he lives, he drops dark hints of a new plot. Sabine decides it's time to send Sherlock a new code.

In the 1970s, young Jim tries to save his family further trouble.

Series 1, Episode 4: Along with the Following Diabolical Device

Sherlock takes on a case involving the apparent suicide of a celebrated interior designer, but the trail leads him back to Sabine, and Sabine back to him.

In the 1970s, Mr Moriarty decides to separate young Jim and Sabine by sending them away.

Series 1, Episode 5: A Problem in the Doctrine of Chances

Realizing it's too dangerous to continue, Sabine delivers a dire warning- along with a hint about her past. John extracts an awkward confession, and the message in the mirror reappears.

In the 1980s, teenage Sabine and Jim reunite for a few stolen moments at a family funeral.

Series 1, Episode 6: Symbols, Signals, and Noise

Sabine gives Sherlock her mobile number, forbidding him from calling her- leaving Sherlock to interpret the message.

In the early 1990s, young Sabine arrives at Oxford University, and is delighted to find her brother there- a changed man, and in love.

Series 1, Episode 7: A Treatise on Electricity and Magnetism

Gregson reveals that Sherlock's secret source is no secret to him. Aidan brings a message to Sabine, and Sherlock winds up the Gary Elliot case - or so he thinks.

Back at Oxford in the 1990s, young Sabine settles into life as Jim and Anthony's third wheel.

Series 1, Episode 8: Decoherence

Sabine finds her double life increasingly difficult to maintain. Gregson moves in to take over the Elliot investigation, but begins to behave strangely.

Back at Oxford in the 1990s, young Sabine begins to take more of an interest in Anthony and Jim's business.

Series 1, Episode 9: On Physical Lines of Force

The recent murders cause Sabine and Sherlock to suspect each other. Sherlock's brother Mycroft instantly sees through Sherlock's odd behaviour.

Back in the 1990s, young Jim is expelled from Oxford, and decides to go out in style.

Series 1, Episode 10: On Reasoning in Games of Chance

Sabine participates in a unique scientific experiment, which proves astonishingly successful. John's patience with Sherlock runs out, and Jim leaves Sabine a mysterious gift.

Back in the 1990s, Sabine's studies fall off as she gets more and more entangled in Jim and Anthony's world.

Series 1, Episode 11: The Happy Ending Problem

Sherlock, recovering from the poisoning, decides he must solve the problem of Jim once and for all.

Back in the 1990s, young Sabine plays her part in the Appelmans safecracking, but both Anthony and Jim make it awkward for her.

Series 1, Episode 12: Solvable and Unsolvable Problems

In this prelude to next week's series finale, Jim warns Sherlock that he's playing with fire.

Back at Oxford in the 1990's, Sabine is exasperated when her brother and Anthony both try to control the terms of the marriage. Aidan despairs that Sabine is making the wrong choice.

Series 1, Episode 13: (FINALE) On Formally Undecidable Propositions

In the Series One finale, Sabine and John follow Sherlock's trail to Reichenbach Falls, while in the 1990s, Sabine's wedding preparations are brutally cut short by news of Anthony's death.