  Galaxy clusters grow primarily through the continuous accretion of
group-scale haloes. Group galaxies experience preprocessing during their
journey into clusters. A star-bursting compact group, the Blue Infalling Group
(BIG), is plunging into the nearby cluster A1367. Previous optical observations
reveal rich tidal features in the BIG members, and a long H$\alpha$ trail
behind. Here we report the discovery of a projected $\sim 250$ kpc X-ray tail
behind the BIG using Chandra and XMM-Newton observations. The total hot gas
mass in the tail is $\sim 7\times 10^{10}\ {\rm M}_\odot$ with an X-ray
bolometric luminosity of $\sim 3.8\times 10^{41}$ erg s$^{-1}$. The temperature
along the tail is $\sim 1$ keV, but the apparent metallicity is very low, an
indication of the multi-$T$ nature of the gas. The X-ray and H$\alpha$ surface
brightnesses in the front part of the BIG tail follow the tight correlation
established from a sample of stripped tails in nearby clusters, which suggests
the multiphase gas originates from the mixing of the stripped interstellar
medium (ISM) with the hot intracluster medium (ICM). Because thermal conduction
and hydrodynamic instabilities are significantly suppressed, the stripped ISM
can be long lived and produce ICM clumps. The BIG provides us a rare laboratory
to study galaxy transformation and preprocessing.
