Three years after the release of their self-titled debut EP, Sydney progressive-rock quintet Mercury Sky are set to release their sophomore EP ‘Infra’.

They toured their debut extensively, sharing the stage with the likes of Bellusira, Sleepmakeswaves and Breaking Orbit and cementing their place as a must-see live act. ‘Infra’ was produced by Dave Petrovic (Cog), the same producer responsible for their first release, as well as the band taking on a large part of the production duties themselves.

Mercury Sky have really elaborated on their sound and style with this EP. The opening song ‘Sosonal’ was originally released as a single at the end of 2015 and serves as a fantastic introduction. It’s a great demonstration of what to expect from these guys. Smooth flowing lead guitar passages decorating the heavy low-end. Then you hear the unconventionally wonderful voice of Kay Thatch. Appropriate adjectives are difficult here; needless to say it is a voice that will get your attention.

No True Scotsman’ begins with a very Karnivool-esque feel. While the vocal parts and harmonies are written by Thatch, the laudable performance in this song is from guitarist Kieren Lovett who not only provides his challenging string-work; he also contributes absolutely solid backing vocals. The bridge is an accumulating section including softer vocals and acoustic guitar which explodes into the first display of competently executed dirty vocals and a heaviness that’s so diametrically opposed it almost doesn’t fit. This is a foundation of the Mercury Sky sound that they implement seamlessly.

The curiously titled ‘PreCious’ channels The Foo Fighters and Twelve Foot Ninja. The bass of Tom Bergman dominates the verses, combining perfectly with Kieran Berry’s immaculate, progressive drumming. The feature is a fuzzy electro breakdown with a whispered vocal part which moves into one of the heavier sections on the EP. Two things will happen after you hear ‘PreCious’: You will have a repetitive voice in your head whispering ‘don’t breathe, don’t move, don’t…’ and the chorus will earworm you for days after. You have been warned.

SleepDreamWake’ brings the pace down dramatically. This is an emotion-invoking piece, not soaked in riffs and double-kicks, but equally as potent. Cameron Davies provides a beautiful guitar solo and some dreamy lead guitar overall. In a constant attempt to convert people to heavier music, this is an example of very accessible music to persuade people into to seek out more heavy riffs and complex time signatures. For one of the longer, slower songs, it remains engaging throughout the whole track.

The highlight track, for this writer is ‘Blue and Purple’. It is the highlight mainly because it’s the most dynamic song across all the instruments and is not dominated by anyone in particular. It is the best example of all 5 members in full flight together. There is a subtle A Perfect Circle influence at play, especially in the latter half and yet again, Thatch is in fine form.

The final song ‘Nausea’ is the first new single off the EP and has already drawn a lot of positive attention. A gentle intro builds into a slow groove which further expands into a furor of screams and labyrinthine rhythms. ‘Nausea’ is a great conclusion to the EP.