Grantchester is like a jigsaw puzzle, and the trick or the fun is in working out how the separate bits fit together.

Within the first ten minutes of this week’s third episode, for example, we’ve been given all the pieces.  The murdered husband.  The catholic wife.  The mechanic.  The secretary.  The lady at the post office.  The armed robbers.

Did the wife kill the husband?  No, that doesn’t quite fit.  Is she having an affair with the mechanic?  No, that’s not quite right either.  Has she secretly had an abortion, hence the catholic guilt trip?  Yes – and the mechanic went with her for support, that all slots together nicely.  In that case maybe the secretary is our killer?  That makes more sense, now we’re really getting somewhere.

What about the Post Office robbers though, “our very own Bonnie and Clyde” as ambitious ‘tec Phil calls them?  They don’t seem connected to the rest of it.  Unless…  unless we add in the suggestion of an illicit relationship, and the revelation that it’s actually their very own Bonnie and Bonnie, the killer secretary and the lady at the post office working together.  (The lady at the post office, for no real reason, adopts Bonnie’s iconic ‘beret and bandana’ look for the final showdown, just to underline the point.)

The whole picture, when it’s finally all put together, is pretty satisfying, and there’s of course a certain skill required to produce something which allows the audience to think themselves a step ahead of the cops while at the same time not giving the whole game away too early.

Detective work may be easily tied up within the hour, but not everything in Grantchester is as simple.  Despite his best intentions of breaking it off, Geordie and Margaret are still having an affair.  Meanwhile, after last week’s absolute and mutual certainty that they can only ever be friends, Sidney and Amanda are apart… well for fifty-five minutes they are, after which his sermon about living for the moment gets Sidney so hot under the dog collar that he marches around to Amanda’s house and takes her on the staircase.  If sermons genuinely have that effect, no wonder Grantchester’s pews are always so full.

But while the rest of the cast is busily breaking the sixth and seventh commandments, the real star of the show continues to be Al Weaver as unworldly, bookish, well-intentioned curate Leonard.  His proposal to Miss Franklin is as sweet and undramatic as he is, and even though we know that he knows he’s gay, his good intentions can’t really be questioned.  There’s talk of contentment and ease and liking, rather than of love and romance and passion; but nevertheless it’s a proposal promptly accepted.

Geordie’s decision is which woman to be with, and Sidney’s choice is between his calling and the woman he loves.  But for Leonard it’s a no-win situation, and whether he marries or not it won’t really mean a happy ending for him.

More puzzles next week…

Aired at 9pm on Sunday 7 May 2017 on ITV.

Buy Season 1 on DVD on Amazon here.

Buy Season 2 on DVD on Amazon here.

What did you think of this week’s episode? Let us know below…