Desmond's fail-safe key with "Joe Inman" dog tag
Embossed with the DHARMA Initiative/Swan logo, the fail-safe key is kept by Kelvin Joe Inman until the day of the system failure and the crash of Oceanic Flight 815 when Desmond accidentally kills him and takes the key, which he then hides inside his copy of Charles Dickens' "Our Mutual Friend." After Locke causes another system failure by destroying the computer, Desmond retrieves the key and triggers the fail-safe mechanism, finally terminating the electromagnetic anomaly (and preventing a global catastrophe) and resulting in the destruction of the Swan station.

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