The cover-up has quietly changed jobs. It used to be the thing you pulled on between the water and the sunbed, and it was designed to be forgotten. Now it is often the most considered piece in the suitcase.

Missoni made that case directly in June, presenting Resort 2027 under the title Waterfront Master Blaster. Alberto Caliri framed the collection around summer as a mood rather than a location, with pieces meant to move between beach and city. The showroom racks were sorted by colour instead of by gender or category, women's resort hanging beside men's spring and bath textiles in between. Caliri calls the underlying idea Missonism, the house's habit of imposing order on exuberance. The same logic runs through the Missoni Resort Club destinations, which include Portofino, Costa Smeralda, Mykonos and the Maldives, places where lunch and dinner are the same outfit with a change of shoes.

Which raises the practical question. When does a cover-up genuinely work as a dress, and when does it just look like you forgot the rest?

Opacity. Hold it up to daylight. If you can read your hand through the body of the garment, it is a cover-up and it will stay one. Missoni's mesh and tulle pieces are built to sit over swimwear, and no styling turns them into a standalone dress. The lame viscose pieces are the ones that work alone, because the metallic thread closes up the weave.

A defined waist. A caftan with no waist is a tent, and it reads as a robe in any setting with a table. Look for a tie, a seam, or enough drape that a belt will hold. The Caftan cover-up with irregular zig zag print takes a belt cleanly.

Length. Mid-calf and floor length pass as dresses. Anything ending high on the thigh does not, no matter what you pair it with.

One more thing worth knowing about the fabric. These are mostly viscose, which drapes fluidly and feels cool because it absorbs moisture readily, but loses strength when wet. Rinse the salt out in cold water and dry it flat rather than on a hanger, or the weight of the water will stretch the shoulders.

The trick is one non-beach element. Not three. One.

Trousers under a long cover-up is the most reliable version and the least obvious. It sounds like too much fabric and it is not, because the cover-up reads as a long open layer rather than a dress once there is a trouser leg beneath it. A wide lame trouser under an open caftan is a genuinely urban outfit, and it is roughly what Caliri showed when he layered shirts over one another and put knitwear with denim.

A proper shoe is the other lever. The same caftan is beachwear with a flat sandal and dinner with a heel, and nothing else about the outfit has to change.

What does not work is trying to hide the swimwear underneath. If the cover-up is opaque enough to be a dress, wear normal underwear beneath it. A visible bikini tie at the neck tells everyone the garment's real job, and it undoes the whole effort.

Can you wear a cover-up to dinner? Yes, if it is opaque, at least mid-calf, and has a waist. Change the shoe and add one accessory that has nothing to do with the beach.

What is the difference between a caftan and a cover-up? A caftan is a shape, a long loose robe with wide sleeves. A cover-up is a purpose. Plenty of caftans are cover-ups, and plenty of cover-ups are not caftans.

What do you wear under a cover-up dress? If it is opaque, ordinary underwear. If it is sheer, either swimwear you are happy to have seen or a slip. Do not try to make sheer work with underwear intended to be invisible.

Are cover-ups worth the money? Only if they pass the opacity test. A sheer mesh piece is beautiful and it has exactly one use, so price it against a few beach days rather than a wardrobe.

How do you pack one? Roll it. Viscose creases hard when folded and the crease will still be there at the hotel.