It's the plotline that's got the whole country gripped.

The 54-year-old businessman Thomas Henderson was getting into his car outside the offices of City law firm The Firm, when the assailant pulled up alongside and fired three shots into his chest. A hospital spokesman said that Mr Henderson's condition was critical and that "somehow the attacker had injected him with a massive quantity of cocaine as well".

East London Echo, 13 February 2001.

So here's your indispensable bookies' guide to who shot Tom Henderson:

Evens: Bartholomew Chalmers

A double first from Cambridge led to little in the legal world after he joined The Firm in 1997. Recently, Henderson made him wear a nappy and sit in a cupboard for eight days straight as punishment for letting the photocopier run out of headed A4. He's not scared of prison – in fact, he'd look forward to the break.

2-1: Alison Brett

The head of corporate at The Firm has every reason to keep Henderson alive – she supplements her basic drawings with thousands in sexual harassment claims every year. Then again, in The Firm's new notepaper she is listed as "Sweetlips".

5-1: William "Big Tosh" Toshington

Burly security guard Tosh wouldn't hurt a fly – unless, of course, he's been reminded of his time fighting the VC in 'Nam. Besides, witnesses report seeing him in his security cubbyhole watching Vets in Practice on BBC1.

10-1: Rodney Bickerthwaite

There was a blazing incident two days prior to the shooting when Henderson was heard to remark that "David Gower had to be the most gifted batsman we've had at test level". But the attack was too quick – Bickerthwaite would have surely spent hours crafting his onslaught.

50-1: Senior partner Jack Pratchard

A lifelong friend of Henderson, it's unlikely that he pulled the trigger. On the other hand, he once burnt off his ear after the phone rang while he was ironing. And he often can't remember who Henderson is.

75-1: Don Maclean (the PR machine)

Motive – he's a player. Opportunity – Maclean says he can have anyone "rubbed out" for £50. Reality – he lives at home with his alphabeticised collection of Star Trek: Deep Space Nine episodes. Besides, "he was having his tea at the time," said his spokesmum.

100-1: a client

Henderson's portfolio does include the El Ramerez brothers, who are known to run a Colombian import-export firm trading in – according to its brochure – "naughty salt".

250-1: the OSS

The OSS has realised that it can radically reduce its workload by cutting off the complaints at their source. Tom Henderson is currently responsible for a third of all complaints to the profession, including exhorbitant billing, slow work, inadequate service, blackmail, extortion, murdering a client and taking longer than seven seconds to answer the phone.

500-1: the senior partner of a rival firm

Over the years, Henderson has been rather crudely and smuttily critical of a number of City practices, including Pinsent Curtis, Simmons & Simmons, Davies Arnold Cooper, Simmons & Simmons, Slaughter and May, Simmons, Denton Wilde Sapte, Simmons and, of course, Simmons.

1000-1: the DTI

They got him once, imprisoning him in Ford Open Hotel, where he was forced to endure life without Sky Sports 2 and share The Sunday Telegraph magazine. But since then, despite a secret source inside The Firm feeding them info every two weeks hidden at the back of The Lawyer, he's evaded them at every turn.

2000-1: Robert Sayer

Well, he is a loose cannon.

Out of respect to Mr Henderson and his family, The Firm will not be appearing for the next two months until his condition improves. Or he dies. We haven't decided yet. It is, after all, fictional.