When a four-year old pipe bomb detonates in a computer company's offices, killing two, Sherlock Holmes (Jonny Lee Miller) helps Captain Gregson (Aidan Quinn) find the bomber on this week's Elementary episode "The Long Fuse." It's not an easy task, since the bomb has been hidden in the ventilation system for years, long before the computer firm took over the space.
The likely target is the former tenant of the office space that had vacated the space four years earlier — a crisis communications firm headed by Heather (Lisa Edelstein, House, M.D.). The firm certainly had its share of enemies, particularly an eco-terrorist organization called ELM that had a habit of detonating environmentally conscious explosive devices at businesses it opposed.
But ELM's not responsible for this deadly bombing. Perhaps, instead, the bomber is a former (and perhaps disgruntled) employee, who had disappeared right around the time the bomb originally was to have detonated. But when he turns up dead — and hidden within the walls of his own home — Sherlock realizes the motive was rather more personal.
How better to conceal a murder than with a copycat bombing? The string of ELM bombings must have seemed to Heather, a convenient idea to cover story to rid herself of an embarrassing employee — one who could (and had threatened to) expose her past as a hooker. But when the bomb failed to detonate, she'd found another way to dispose of her blackmailer — quite literally.
Sherlock's keen memory, uber observational skills, his heightened sense of smell, and even his penchant for crossword puzzles combine to help identify Heather as the bomber/murderer.
Sherlock seems a bit worried, though not so much in words as expression, by the imminent departure of sober companion Dr. Joan Watson (Lucy Liu). She has only six weeks left on her contract with Sherlock's father, and then she will be gone. She tries to help him identify a permanent sponsor — a former addict — to help him through his long-term recovery.