From the author of the #1 Bestselling Audible Thriller of the Year comes a terrifying high stakes hunt to the death…

It is the winter solstice, the longest night of the year.

When a New York Senator is chosen as an assassination target by Colosseum, the chilling online game, she faces a terrible choice; to run or to hide.

No-where is safe. No-one can be trusted.

But just when the Senator’s brutal death seems inevitable, a young agent arrives from London to protect her. Now Winter is all that stands between the Senator and Colosseum’s deadly hunt. As dawn creeps in, time is running out for Winter to unravel the mystery at the heart of this sinister game: who is the shadowy head of Colosseum, and what is his ultimate purpose?

It is darkest before the dawn.

As Winter and the Senator journey together into the dark heart of the longest night, they soon discover that nothing about Colosseum is what it seems. There are rules, and there is a purpose, if only they can solve the riddle in time. Colosseum is more than a hunt: it’s a challenge.

Targets must face their deepest fear, or die at dawn.

Praise for The Winter Series

‘Wow! Double wow!! Triple wow!!!… If this is what Winter is like, I don’t like the other seasons anymore.’ B for Book Review, 5 stars

‘A clever, original spy thriller…gripping, pacy and highly original. Highly recommended.’ Goodreads reviewer, 5 stars

‘perfect for fans of le Carre, Fleming and those looking to start a riveting new thriller series’. - Audiofile magazine

‘There is a new kid on the block - the love child of Jack Reacher and Lisabeth Slander….she can out-punch Bourne and out-pull Bond. - Andy Martin, author of Reacher Said Nothing

'YES! YES! YES! That is how you write an action thriller. The pace is relentless. This is pure action… I highly recommend this for action junkies and anyone who likes a tense thriller.’ Goodreads reviewer, 5 stars

‘If you are looking for an action-packed suspense thriller with a kick-ass heroine government agent, then this is the book for you.’ The Book Nurse, 5 stars

‘Heart-pounding danger with a female James Bond. Total adrenaline fest! The writing is top-notch and I would put Callister’s action series against the best in the genre - Jack Ryan, move over!’ Goodreads reviewer, 5 stars

‘A thrill-a-minute, edge-of-your-seat thriller that will have you quickly turning the page… will keep you entertained and engrossed until it’s thrilling denouement. A great read that will spike your blood pressure accordingly - not for the faint-hearted!’ Goodreads reviewer