Phase Shift is the thrilling final instalment in Jenn Burke and Kelly Jensen’s fantastic Chaos Station sci-fi romance series, and it’s a terrific last hurrah for Zed, Felix and the crew. But of course, there’s no way any swan song featuring these characters isn’t going to put them – and us – through the wringer, and Zed and Felix’s agreement (made in Inversion Point) that “This nearly dying shit has got to stop” is sorely tested.

When the book opens, the different species of the universe – even the stin – appear to be peacefully co-existing, the Guardians are quiet, and the crew of the Chaos aren’t running for their lives. Win! So Zed has taken the opportunity to plan a romantic dinner for himself and Felix, intent on asking a very important question – which is promptly derailed when their friend Marnie interrupts their evening with the news that the Chaos is being hacked. A furious and seriously affronted Felix (how dare anyone fuck with him like this?!) rushes out to find out what’s happening and stop it if he can, and Zed heads out into the busy station docks while Felix works. A quick call to Elias, Nessa and Qek has them all on the trail of the hacker, who is making their way towards the marketplace. But just when they think they’ve got whoever it is cornered – they disappear, phase shifting the way Zed is able to do. Which is impossible. All the other subjects of Project Dreamweaver are dead and Zed is the only human live able to mimic the stin’s phase-shifting abilities. So who – or what – the hell were they just chasing?

Returning to the ship, the crew discovers that the hacker targeted their medical logs and downloaded everything they had on file about Project Dreamweaver. When Felix, Marnie and Ryan trace the packets of data to somewhere out near resonance space, things begin to fall into place. The only reason for anyone to be out there would be to get hold of a crystal shard, a piece of the resonance, which is needed in order to create fully functional and stable super soldiers. The planet Leonis Bb is in a barely mapped area of space, making it an ideal secret location for another experimental program. But who could be behind it? While Elias, Nessa and Qek take the Chaos to Petrel Station to warn Marnie and Ryan that they might need to make themselves scarce, Zed and Felix borrow one of the ships from the Anatolius Corporation’s fleet and head off to Leonis Bb – supposedly an uninhabited planet – to see what they can find out.

Phase Shift is a rollicking, action-packed old-skool sci-fi adventure that keeps the adreniline pumping and the reader eagerly turning pages, desperate to find out what happens next. After a crash landing that leaves Zed with a broken wrist and a concussion, our heroes are stranded on an inhospitable planet with few supplies, limited technology and no way to send a distress signal. When they discover that this supposedly uncolonised planet is home to a rag-taggle band of illegal colonists living off the grid it’s not too much of a surprise – but what they hadn’t expected to find there is their worst nightmare, revived. Dr. Carlisle Preston, the lead medical specialist for Project Dreamweaver, has re-started the super soldier program and is already experimenting on the colonists, but she needs one more ingredient to ensure their stablity – a crystal shard from the resonance – and someone to train her newest lab-rats. And the ideal solutions to both those problems have just crashed (literally) on her doorstep. But there’s a bigger threat out there in the form of the mysterious Guardians, who have an agenda all their own and who will do whatever it takes to ensure they get what they want.

The authors have done an incredible job of keeping the momentum going from book to book while also having each one be (more or less) a standalone story AND maintaining the quality of the plotting and storytelling throughout. Each book in the series is a fabulously entertaining read and the development of the central romance between Zed and Felix has been spectacular. The reader has known since the beginning that they’re a forever deal, although it’s taken Felix, especially, a while to really believe in it, to believe that he deserves good things and that Zed isn’t going anywhere. By the end of Inversion Point it seemed they were finally on the same page, ready to make a life together and face whatever it threw at them, but there’s one hurdle still to be faced; Zed wants to get married, and commitment shy Felix is, not to put too fine a point on it, not keen. But crash-landing on an unknown planet, being taken prisoner by a mad scientist, and having to make a locator/beacon out of a piece of string and two paper clips (or whatever the twenty-third century equivalent is!) aren’t going to deter Zed from continuing the conversation he’d planned to start back on the Chaos, and in between all the running for their lives and blowing shit up, there’s still time for some quieter, more intimate moments and some emotional gut-punches.

All the Chaos Station books incorporate a just about perfect blend of action, romance, intrugue and humour. The plots and story-arcs are brilliant and well-executed, the worldbuilding is strong and imaginative, and the deep emotions and angst are never manufactured, deriving organically from who these people are and how their experiences have informed their beliefs and actions.

If I have a criticism it’s that the late-book ‘death’ is perhaps just one too many, but it’s so skilfully done, I was completely sucked in (and honestly, didn’t care!)

As in the other titles in the series, this reissued edition includes a short story from the Always and Forever collection, this one entitled, simply, Honeymoon. Zed and Felix have tied the knot and opted to go on a space cruise for their honeymoon – which is perhaps not the best choice for two men for whom ‘downtime’ is an almost unknown concept!

Phase Shift brings this outstanding sci-fi romance to a close and brings Zed and Felix their very well-deserved HEA. Some series go downhill over time, but this one absolutely doesn’t – each story has been a rollercoaster ride of thrills, spills and emotional peaks and troughs, and I’ve loved every minute of the time I’ve spent with these characters and in this universe. Thank you Jenn and Kelly – it’s been a blast!