How is Electric Dreams episode Human Is different from Philip K Dick's original story?

When our main character Vera's husband Silas returns home to Terra after battling aliens, she discovers his personality has completely changed – but is he actually more human, or less?

We should say upfront that this article contains SPOILERS for both the TV show and Philip K Dick's short story. But if you're wondering what happened in the original plot, read on.

Does the TV show follow the same plot as Philip K Dick's original story?

Of all the episodes we've seen so far, this one comes closest to the original plot, fleshing out the sci-fi author's 17-page short story. Mecklenburg explains: "I reimagined Jill and Lester, calling them Vera and Silas, while retaining as much of the nuance and honest emotion of Philip K Dick's original story as possible."

In Human Is we meet Jill Herrick, the unfortunate wife of ruthless Lester Herrick. He's a "monster", cruel, demanding and abusive, telling Jill she can never see her young nephew Gus again and even tormenting the boy himself. He's also extremely successful at his job.

When Lester is suddenly deployed to Rexor IV, Jill dreads his return and even makes up her mind to end the marriage. But when he walks through the door he is a "different man".

This version of Lester speaks in old-fashioned phrases ("Do I smell a delicious repast warming on the hearth?"). He treats her lovingly and even thanks the robot who takes his coat. He is delighted by everything, from ice cream to coffee to his young nephew Gus. The only thing he doesn't really care about is work.

Jill confides in her brother Frank, describing all the weird but wonderful changes she's noticed in her husband. Frank is extremely concerned and drags Lester off to be examined by some Federal Clearance Agents. It seems this man isn't Lester at all: he's a Rexorian infiltrator. The old Lester's personality has been removed and stored in suspension, and substituted with this alien.

Frank explains: "The Rexorians are an old race. The few that remain are feeble. They've been trying to migrate for centuries. But their bodies are too weak. Some tried to migrate to Venus – and died instantly. They worked out this system about a century ago." Since then the Rexorians have studied the language, customs and manners of humans from old Terran books, which is why Lester has suddenly gone old-fashioned.

Seeing as "Lester" has got all the way home to Terra, the Clearance Agents can't just remove the Rexorian from his body: they have to prove they're right in a court of law. So they bring Jill in to testify.

But Jill is actually quite happy with this version of Lester, thank you very much. She doesn't want her husband's original "contents" back. So she feigns ignorance: "What changes are you talking about?"

Lester and Jill walk home free, while this Rexorian enjoys the smell of spring in the air. He gazes at his wife tenderly, putting an arm around her shoulders and promising to do "whatever will make you happy".

How is Channel 4's Electric Dreams adaptation different from the original?

Mecklenburg has given the story more depth, but stayed true to Philip K Dick's narrative.

In this version Jill (now called Vera) is a high-ranking official herself: she works alongside her husband. The TV version also removes little Gus from the equation, even though he was a flashpoint for conflict in the original story. Instead, the focus is on Silas' emotional abuse of his wife: his cruelty and ruthlessness, his lack of emotion or physical desire. That rejection forces Vera to find sexual satisfaction elsewhere at some kind of fancy sex dungeon.

At work, Vera has a second-in-command named Yaro, who becomes a replacement for the man we originally knew as "Frank". It is Yaro who sounds the alarm when Vera confides in her that Lester has come home a different man. With the relationship between Yaro and Vera, we see the grey areas: how do you balance friendship with patriotic duty? Where do loyalties really lie?

The final key difference comes in the courtroom scene. In Philip K Dick's version, the Clearance Officers were forced to accept Jill's testimony – but in this adaptation she fails to convince the court that Silas is human. Because of her high-ranking position, she herself comes under suspicion for treason, with Yaro accusing her of knowingly hiding a Rexorian and concealing the truth from the court.

Silas strikes a bargain with the court: if they let his wife go free, he'll admit to being a Rexorian and face the death penalty. The judge agrees.

But Vera has a brainwave: if Silas is willing to sacrifice himself for love, she argues, surely he can't be an evil Rexorian? So just as we saw in the original story, Silas and Vera go free. They share a romantic moment where the Rexorian agrees she can still call him Silas.

Oh, and one more difference: he doesn't use old-fashioned language. Which indubitably is a crying shame.

Electric Dreams returns to Channel 4 in 2018 with the final four episodes