The secret of the lost tunnel

Series: Hardy Boys mystery stories

• The tower treasure (Volume 1.)

• The house on the cliff (Volume 2.)

• The secret of the old mill (Volume 3.)

• The missing chums (Volume 4.)

• Hunting for hidden gold (Volume 5.)

• The shore road mystery (Volume 6.)

• The secret of the caves (Volume 7.)

• The mystery of Cabin Island (Volume 8.)

• The great airport mystery (Volume 9.)

• What happened at midnight (Volume 10.)

• While the clock ticked (Volume 11.)

• Footprints under the window (Volume 12.)

• The mark on the door (Volume 13.)

• The hidden harbor mystery (Volume 14.)

• The sinister signpost (Volume 15.)

• A figure in hiding (Volume 16.)

• The secret warning (Volume 17.)

• The twisted claw (Volume 18.)

• The disappearing floor (Volume 19.)

• Mystery of the flying express (Volume 20.)

• The clue of the broken blade (Volume 21.)

• The flickering torch mystery (Volume 22.)

• The melted coins (Volume 23.)

• The short-wave mystery (Volume 24.)

• The secret panel (Volume 25.)

• The phantom freighter (Volume 26.)

• The secret of Skull Mountain (Volume 27.)

• The sign of the crooked arrow (Volume 28.)

• The secret of the lost tunnel (Volume 29.)

• The wailing siren mystery (Volume 30.)

• The secret of Wildcat Swamp (Volume 31.)

• The crisscross shadow (Volume 32.)

• The yellow feather mystery (Volume 33.)

• The hooded hawk mystery (Volume 34.)

• The clue in the embers (Volume 35.)

• The secret of Pirates' Hill (Volume 36.)

• The ghost at Skeleton Rock (Volume 37.)

• Mystery at Devil's paw (Volume 38.)

• The mystery of the Chinese junk (Volume 39.)

• Mystery of the desert giant (Volume 40.)

• The clue of the screeching owl (Volume 41.)

• The Viking symbol mystery (Volume 42.)

• The mystery of the Aztec warrior (Volume 43.)

• The haunted fort (Volume 44.)

• The mystery of the spiral bridge (Volume 45.)

• The secret agent on Flight 101 (Volume 46.)

• Mystery of the whale tattoo (Volume 47.)

• The arctic patrol mystery (Volume 48.)

• The bombay boomerang (Volume 49.)

• Danger on Vampire Trail (Volume 50.)

• Masked monkey (Volume 51.)

• Shattered helmet (Volume 52.)

• The clue of the hissing serpent (Volume 53.)

• The mysterious caravan (Volume 54.)

• The witchmaster's key (Volume 55.)

• The jungle pyramid (Volume 56.)

• The firebird rocket (Volume 57.)

• The sting of the scorpion (Volume 58.)

• Night of the werewolf (Volume 59.)

• Mystery of the samurai sword (Volume 60.)

• The Pentagon spy (Volume 61.)

• The apeman's secret (Volume 62.)

• The mummy case (Volume 63.)

• Mystery of Smugglers Cove (Volume 64.)

• The stone idol (Volume 65.)

• The vanishing thieves (Volume 66.)

• The outlaw's silver (Volume 67.)

• Deadly chase (Volume 68.)

• The four-headed dragon (Volume 69.)

• The infinity clue (Volume 70.)

• Track of the zombie (Volume 71.)

• The voodoo plot (Volume 72.)

• The billion dollar ransom (Volume 73.)

• Tic-tac-terror (Volume 74.)

• Trapped at sea (Volume 75.)

• Game plan for disaster (Volume 76.)

• The crimson flame (Volume 77.)

• Cave-in (Volume 78.)

• Sky sabotage (Volume 79.)

• The roaring river mystery (Volume 80.)

• The demon's den (Volume 81.)

• The blackwing puzzle (Volume 82.)

• The swamp monster (Volume 83.)

• Revenge of the desert phantom (Volume 84.)

• The skyfire puzzle (Volume 85.)

• The mystery of the silver star (Volume 86.)

• Program for destruction (Volume 87.)

• Tricky business (Volume 88.)

• The sky blue frame (Volume 89.)

• Danger on the diamond (Volume 90.)

• Shield of fear (Volume 91.)

• The shadow killers (Volume 92.)

• The serpent's tooth mystery (Volume 93.)

• Breakdown in Axeblade (Volume 94.)

• Danger on the air (Volume 95.)

• Wipeout (Volume 96.)

• Cast of criminals (Volume 97.)

• Spark of suspicion (Volume 98.)

• Dungeon of doom (Volume 99.)

• The secret of the island treasure (Volume 100.)

• The money hunt (Volume 101.)

• Terminal shock (Volume 102.)

• The million-dollar nightmare (Volume 103.)

• Tricks of the trade (Volume 104.)

• The smoke screen mystery (Volume 105.)

• Attack of the video villains (Volume 106.)

• Panic on Gull Island (Volume 107.)

• Fear on wheels (Volume 108.)

• The prime-time crime (Volume 109.)

• The secret of Sigma Seven (Volume 110.)

• Three-ring terror (Volume 111.)

• The demolition mission (Volume 112.)

• Radical moves (Volume 113.)

• The case of the counterfeit criminals (Volume 114.)

• Sabotage at Sports City (Volume 115.)

• Rock 'n' roll renegades (Volume 116.)

• The baseball card conspiracy (Volume 117.)

• Danger in the fourth dimension (Volume 118.)

• Trouble at Coyote Canyon (Volume 119.)

• The case of the cosmic kidnapping (Volume 120.)

• The mystery in the old mine (Volume 121.)

• Carnival of crime (Volume 122.)

• The robot's revenge (Volume 123.)

• Mystery with a dangerous beat (Volume 124.)

• Mystery on Makatunk Island (Volume 125.)

• Racing to disaster (Volume 126.)

• Reel thrills (Volume 127.)

• Day of the dinosaur (Volume 128.)

• The treasure at Dolphin Bay (Volume 129.)

• Sidetracked to danger (Volume 130.)

• Crusade of the flaming sword (Volume 131.)

• Maximum challenge (Volume 132.)

• Crime in the kennel (Volume 133.)

• Cross-country crime (Volume 134.)

• The hypersonic secret (Volume 135.)

• The cold cash caper (Volume 136.)

• High-speed showdown (Volume 137.)

• The Alaskan adventure (Volume 138.)

• The search for the snow leopard (Volume 139.)

• Slam dunk sabotage (Volume 140.)

• The desert thieves (Volume 141.)

• Lost in Gator Swamp (Volume 142.)

• The giant rat of Sumatra (Volume 143.)

• The secret of Skeleton Reef (Volume 144.)

• Terror at high tide (Volume 145.)

• The mark of the blue tattoo (Volume 146.)

• Trial and terror (Volume 147.)

• The ice-cold case (Volume 148.)

• The chase for the mystery twister (Volume 149.)

• The crisscross crime (Volume 150.)

• The rocky road to revenge (Volume 151.)

• Danger in the extreme (Volume 152.)

• Eye on crime (Volume 153.)

• The caribbean cruise caper (Volume 154.)

• The hunt for the four brothers (Volume 155.)

• A will to survive (Volume 156.)

• The lure of the Italian treasure (Volume 157.)

• The London deception (Volume 158.)

• Daredevils (Volume 159.)

• A game called chaos (Volume 160.)

• Training for trouble (Volume 161.)

• The end of the trail (Volume 162.)

• The spy that never lies (Volume 163.)

• Skin & bones (Volume 164.)

• Crime in the cards (Volume 165.)

• Past and present danger (Volume 166.)

• Trouble times two (Volume 167.)

• The castle conundrum (Volume 168.)

• Ghost of a chance (Volume 169.)

• Kickoff to danger (Volume 170.)

• The test case (Volume 171.)

• Trouble in warp space (Volume 172.)

• Speed times five (Volume 173.)

• Hide-and-sneak (Volume 174.)

• In plane sight (Volume 176.)

• The case of the psychic's vision (Volume 177.)

• The mystery of the black rhino (Volume 178.)

• Passport to danger (Volume 179.)

• Typhoon Island (Volume 180.)

• Double jeopardy (Volume 181.)

• The secret of the soldier's gold (Volume 182.)

• Warehouse rumble (Volume 183.)

• The dangerous transmission (Volume 184.)

• Wreck and roll (Volume 185.)

• Hidden mountain (Volume 186.)

• No way out (Volume 187.)

• Farming fear (Volume 188.)

• One false step (Volume 189.)

• Motocross madness (Volume 190.)

• Detective handbook