इस कहानी में कपट है।

Because इस is the oblique form of यह.

In Hindi, when a noun phrase is followed by a postposition such as में, से, पर, or को, that noun phrase goes into the oblique form. So:

• यह कहानी = this story
• इस कहानी में = in this story

So यह changes to इस because of में.

में is a postposition meaning in, inside, or within.

Hindi uses postpositions after the noun, not before it like English prepositions. So:

• कहानी में = in the story
• इस कहानी में = in this story

Here, the story is treated like the place or context where the deceit exists.

Hindi very often expresses this idea with the pattern:

X में Y है = There is Y in X / X has Y

So:

• इस कहानी में कपट है
  literally: In this story deceit is

Natural English translations include:

• There is deceit in this story.
• This story contains deceit.
• This story has deceit in it.

Hindi does not need a separate verb like contains here.

कपट means deceit, guile, duplicity, or deceptiveness.

It is a somewhat formal or literary word. It is not the most casual everyday choice in many situations. It often appears in:

• literature
• moral discussion
• religious or philosophical language
• formal writing

Depending on context, related words could be:

• धोखा = deception, cheating, betrayal
• छल = deceit, trickery
• कपट = deceit/guile/duplicity, often with a more literary tone

So कपट is a good word, but it sounds more elevated than some everyday alternatives.

Because कपट is being treated as a singular abstract noun.

Even though deceit is not something you count, Hindi usually treats it grammatically as singular here, so the verb is:

• है = is

If the main noun were plural, you would use हैं instead.

For example:

• इस कहानी में रहस्य है। = There is mystery in this story.
• इस कहानी में कई रहस्य हैं। = There are many mysteries in this story.

So in your sentence, है matches कपट.

It actually is in the oblique position, but कहानी happens to look the same.

Many feminine nouns ending in -ी do not change visibly between direct singular and oblique singular. So:

• direct singular: कहानी
• oblique singular: कहानी

That is why the change is visible in यह → इस, but not in कहानी.

The most neutral order is:

इस कहानी में कपट है।

This is the standard, natural way to say it.

Hindi word order is somewhat flexible, so other orders are possible for emphasis, such as:

• कपट इस कहानी में है। = It is in this story that there is deceit.
• इस कहानी में है कपट। = more dramatic or literary

But for normal use, इस कहानी में कपट है is the best pattern to learn.

Yes, it is natural and correct, but कपट makes it sound a bit formal or literary.

In everyday speech, depending on the meaning, people might also say:

• इस कहानी में धोखा है।
• इस कहानी में छल है।
• इसमें बहुत कपट है।

So the sentence is perfectly good Hindi, but its tone is a little more elevated than casual conversation.

No. Hindi does not use articles the way English does.

So Hindi can simply say:

• कहानी = story / the story / a story, depending on context

In your sentence, इस already gives specificity, because it means this. So:

• इस कहानी = this story

No extra word is needed for the.

A common transliteration is:

is kahānī meṅ kapaṭ hai

A few pronunciation notes:

• इस = is
• कहानी = kahaa-nee
• में = roughly mein, with nasalization
• कपट = kapaṭ, with a retroflex ṭ sound
• है = hai, pronounced more like heh/hai than English hay

A natural rhythm is:

is kahānī meṅ kapaṭ hai

The sentence is usually spoken smoothly, with no heavy stress unless you are emphasizing a word.