The Hunt for the Yeti Skull (Book 13) Jack has become the most decorated secret agent for the Global Protection Force, but during the day he's still just an ordinary kid who has to put up with annoying people -- like Marko Mayer, a new student in Jack's rock-climbing class. When Jack and Marko race to the top of the wall, Marko stomps on Jack's hand and wins -- then has the nerve to gloat! But Jack has no time to sulk -- the GPF needs him in Nepal. A plane carrying a team of scientists has gone missing over Mount Everest. They were thought to be carrying the first true Yeti skull ever recovered -- proof that the legendary Abominable Snowman really existed. Jack quickly discovers that a greedy collector is behind the theft -- and he may have hired Jack's archnemesis for the job. Can Jack and his fellow agents use their climbing skills to brave the highest mountain on earth and recover the priceless skull?

Jack finally receives a coded message from his brother Max, possibly detailing his whereabouts. But duty calls, and Jack is whisked away to the sweltering savannah of Kenya before he can decipher it. Once there, a wise and kind Masai chief alerts Jack to a series of elephant killings where the corpses have been robbed of their tusks. Jack must find the malevolent ring of poachers responsible before more of these endangered species are destroyed.

In The Caper of the Crown Jewels, Jack is summoned to solve a matter of grave national importance: the theft of the Crown Jewels of the British Empire from the Tower of London. Arriving on the scene, he is greeted by a traditional Tower guard- a Yeoman Warder (or Beefeater)- who explains what's missing: The Imperial State Crown, the Sovereign's Orb, and the Sovereign's Scepter with the cross containing the finest-cut diamond in the world, the Star of Africa. Jack identifies Ivan the Incredible and his assistant, Jazz, as the thieves immediately--but puzzling out how they did it is stickier. The famous Tower has the most advanced security in the world, and even using his impressive gadgets (the Encryption notebook, Heli-Spacer, Rock Corer, and Rope Tornado) Jack is flummoxed by how the jewels were spirited out. However, Jack can conjure up more than gadgets--he foils the evil magicians with some powerful mojo of his own, dispels an invisibility enchantment, and narrowly avoids the executioner's block before restoring the jewels to the crown and earning the gratitude of the Queen herself!

When a plane goes missing over Mount Everest, Jack and his fellow agents must brave the highest mountain on Earth to recover its cargo--the first true yeti skull ever recovered.

Jack Stalwart may be a top rock climber, but no amount of practise can prepare him for the most gruelling climb of all: Mount Everest. When a skull believed to be that of a yeti is stolen by an evil collector of curiosities, Jack must brave one of the most inhospitable places on earth to retrieve it...

A group of scientists have gone missing in the Arctic - could this be linked to their research into global warming? Jack must face the harsh weather and a very hungry polar bear to find out . . .

On the eve of the first manned mission to Mars, a madman has kidnapped the space project's chief engineer. Can Secret Agent Jack Stalwart save the day and keep his cool when he finds out who the missing engineer is?