TV's most bizarre endings

Will Alex Drake (Keeley Hawes) ever make it back to the Noughties?

Have you been baffled by Ashes to Ashes? Has Lost left you flummoxed?

The two fantasy TV shows conclude this weekend with final episodes that may (or may not) tie up all those puzzling plot threads.

As if that's not enough, the US action drama 24 - starring Kiefer Sutherland as special agent Jack Bauer - makes its final appearance on Monday on Fox after eight years.

In time-travel police show Ashes to Ashes (BBC One Friday at 2100 BST) DCI Gene Hunt will fire up the Quattro for the last time - but will his darkest secrets be revealed?

Meanwhile in the US, the final episode of Lost (ABC on 23 May and 24 May on Sky One) has a formidable job on its hands.

Will we learn the reality behind the lives of the aircrash survivors (and polar bears) who've spent 121 episodes on a tropical island in the South Pacific?

Evangeline Lilly, who plays Kate Austen, recently joked on the David Letterman show that the events of Lost had all been a dream.

It's a device that's been used many times before but not one that's likely to be repeated on Lost, according to Trevor Kimball, senior editor on the website TVSeriesFinale.com.

"They've been planning this for years so I don't think they'll make it all a dream or purgatory, or anything obvious like that," he says.

"It's a very complicated series and - love it or hate it - I don't think the answer is going to be simple. There are a lot of mysteries to wrap up."

Kimball, who is based in Los Angeles, set up TVSeriesFinale.com five years ago.

"I'm one who likes some sort of closure, I was tuning into TV shows just to see how they wrapped things up," he admits.

He cites the last episode of US sitcom Roseanne in 1997 as a bad example of how to end a series.

It emerges most events in the previous series were not what they seemed - and were part of a story being penned by Roseanne.

"It was pretty terrible," says Kimball. "We find out that one character that was gay wasn't gay, and one that was straight was gay.

"It didn't end very well at all and a lot of people felt ripped off by it."

He adds: "For writers it's a very delicate balance - you want to provide closure, but don't close the door too hard. People want to see that characters are moving on just a little, but are still doing the same thing."

Here we look at three TV series finales that left viewers delighted/surprised/perplexed (delete as appropriate).

The Prisoner

Patrick McGoohan as Number Six in The Prisoner

The back story: A former secret agent Number Six (Patrick McGoohan) finds himself trapped in The Village, a mysterious prison guarded by giant bouncing balloons.

When: Seventeen episodes from 1967-1968 (originally on ITV).

Final episode: A bizarre court scene, an assembly of hooded figures, a rendition of "Dem Bones". Number Six rips the mask off a hooded figure to find a chimpanzee mask underneath. He rips that off too - to find his own face laughing back...

Final curtain: Number Six speeds along in his car - as he does the opening titles.

In a nutshell: Clear as mud.

Blake's 7

After Blake's disappearance the rebels were led by the cunning Avon (Paul Darrow - centre)

The back story: Blake (Gareth Thomas) and his gang of space rebels battle the evil Federation, led by the crop-haired siren Servalan (Jacqueline Pearce).

When: The sci-fi show ran on BBC One for four years from 1978 to 1981.

Final episode: Having been absent for two seasons, a disfigured Blake reappears posing as a bounty hunter. He is shot by his arch-rival Avon (Paul Darrow) and then the rest of the crew die (in slow-motion) in a shoot-out with Federation troops.

Final curtain: Avon - the only rebel still alive - stands astride Blake's body and raises his gun at the troops. His face breaks into a smile. Freeze frame. Credits roll to the sound of gunfire...

In a nutshell: Bloodbath.

St Elsewhere

The back story: An American medical drama set at St Eligius teaching hospital in Boston. Main characters include Dr Westphall (Ed Flanders), Dr Craig (William Daniels) and Dr Auschlander (Norman Lloyd).

When: 137 episodes from October 1982 to May 1988 on NBC.

Final episode: In a story packed with puns, in-jokes and word-play, Dr Auschlander tries to save St Eligius from closure. The show's final patient is a large opera singer who has lost her voice. But when the fat lady sings...

Final curtain: In a shock revelation, the entire series is revealed to have been in the imagination of an autistic boy.

The scene cuts from the hospital - with snow falling oustide the windows - to a dimly-lit apartment.

Westphall - now a construction worker - arrives home and greets his father (it's Dr Auschlander!) who is looking after the boy, Tommy.

Westphall tells Tommy to put down the snow globe he is holding and wash his hands. The camera zooms in on the snow globe to reveal it contains a model of St Eligius.

In a nutshell: All in the mind