UPDATE 13/4/15 6.00pm: Destiny's House of Wolves cinematic trailer has now gone live, alongside new details of what the expansion will contain.
Bungie has confirmed that the add-on will bring "new story missions, three new competitive multiplayer maps, and a new cooperative strike", as well as a new Crucible mode.
There's no word on a new raid - instead, a new "arena activity" has been teased, named The Prison of Elders. An earlier leak listed the expansion's raid as "The Arena", so this may be somehow related.
Further details are due to be released over the coming weeks, per a schedule of locked data on Bungie's official site.
As expected, the expansion's story centres around a group of Fallen enemies who have betrayed a truce with the Reef's mysterious Queen:
UPDATE 13/4/15 5.05pm: Destiny's next expansion, House of Wolves, will arrive for all platforms on 19th May.
Activision announced the date just now with a new trailer that is currently set to appear at 6pm UK time - it looks like the publisher pushed the button on its press release a little early.
House of Wolves will be Destiny's second major addition, and will arrive nearly six months after December's The Dark Below add-on.
A similar amount of new content is expected as in The Dark Below, and in fact has already been detailed in a thorough Reddit leak.
"The Queen's Fallen have purchased their freedom with Awoken blood," the expansion's description reads. "Hunt down the traitors and your debt to the Queen will be paid."
A new set of story missions and fresh raid will apparently be included, along with three new multiplayer maps and a new strike.
The raid is expected to be set in the currently-unexplorable Reef area.
"Hundreds" of new weapons, armour and gear will also be included - many of which are already pictured in the Reddit post above.
There's also a new, higher level strike playlist (level 28 Vanguard Dragon) and a new level cap for the Weekly Nightfall activity - level 32.
Even House of Wolves' date - May 19th - was included in the previous leak, details of which back up an even earlier leak of Destiny's extensive expansion schedule.
A much larger expansion, code-named Comet: Plague of Darkness, will arrive in September. This is then expected to be followed by two more smaller DLC additions.